Science & Technology

Science and Technology Notes to Prepare for UPSC Online

Section 1 → Physics articles for Civil Services Preparation

  • Systems of Units Measurement
  • Optics – Mirrors & Lenses
  • Fiber Optics & Laser
  • Basics of Mechanics
  • Waves & Oscillations
  • Properties of Solids
  • Fluids Mechanics
  • Heat & Thermodynamics
  • Electricity & Magnetism
  • Modern Physics
  • Space & Astronomical Science
  • Cern & Higgs Boson particle

 

Systems of Units Measurement

The CGS (centimeter, gram, second) system

  • Length is measured in centimeters, mass is measured in grams and time is measured in seconds.
  • Thus centimeter, gram and seconds are the fundamental units of measurement in the CGS system.

MKS (meter, kilogram, second) system 

  • Unit of measurement for length is meter, for mass it is kilogram and for time it is seconds.
  • Thus in this system meter, kilogram and seconds are fundamental units of measurement.
  • This system was used in France and number of other European countries.

 

FPS (foot, pound, second) system

  • Unit of measurement for length is foot, for mass it is pound and for time it is second.
  • This system is used commonly in Britain and the countries that were under its rule.

 

SI system

  • In SI system length is measured in meter, mass in kilogram and time in seconds
  • The SI system or the International system of standards has now replaced all the systems of measurement.

 

Base quantity Name
Length meter
Mass kilogram
Time second
electric current ampere
Temperature kelvin
amount of substance mole
luminous intensity candela

Fundamental & Derived Units

Fundamental Units

  • The units of fundamental physical quantities (length, mass & time) are called fundamental units.
  • These units can neither be derived from one another nor can be resolved into any other units.
  • They are independent of one another.

 

Derived Units

  • Are the units of physical quantities which can be expressed in terms of fundamental units
  • Unit of area can be an example for derived unit. If L is the length of square then L x L = Lis its area. Similarly, the volume of a cube is L x L x L = L3cubic area.

Scalar and Vector Quantity

Scalar Quantities 

  • Measurements that strictly refer to the magnitude of the medium – absolutely no directional components
  • Everything from tons to ounces to grams, milliliters, seconds & volume are all scalar quantities, as long as they are applied to the medium being measured and not the movement of the medium.
  • Two more commonly used scalar quantities in physical calculations are speed and temperature. As long as they are not associated with a directional movement, they remain scalar quantities.

 

Vector Quantities

  • Refers to both the direction of the medium’s movement as well as the measurement of the scalar quantity.
  • Increase/Decrease in Temperature – The measurement of the medium’s temperature is a scalar quantity; the measurement of the increase or decrease in the medium’s temperature is a vector quantity.
  • Velocity – The measurement of the rate at which an object changes position is a vector quantity. For example: If a person quickly moves one step forward and then one step backward there would certainly be a lot of activity; but, there would be “zero velocity.”

Optics – Mirrors & Lenses

  • Light follows a rectilinear propagation (3 * 108m/s)
  • Umbra Point source of light  Shadow (Total dark)
  • Penumbra →Extended source of light Shadow (Partial dark)

 

Plane Mirror

 

Angle of incidence (i) = Angle of reflection (r)

 

 

 

 

 

 

 

 

Image formed on Plane mirrors

  • Virtual & Erect
  • Equal distance & size
  • laterally inverted

 

 

 

 

Concave & Convex Mirrors

 

 

Image formed by Concave Mirror

 

Image formed by Convex Mirror

 

Distinction between a Plane, Concave & Convex Mirror

 

Use of Concave & Convex Mirrors

Concave Mirrors Torch,Vehicle headlightsShaving mirrors,Dentist MirrorConc. sunlight to produce heat  Convex mirrors Rear view mirrorsAlways gives erect though diminished imageProvides wider view 

 

Refraction 

  • Velocity is higher in less denser medium
  • n21= v1/v2 (n21  refractive index of medium 2 wrt medium 1)
  • A ray of light will bend towards the normal if it is travelling from rarer to denser medium & away from the normal if it is travelling from denser to rarer medium

Few examples of refraction

  • Twinkling of stars
  • Sunrise & sunset (we can see the sun 2 min before the sunrise & 2 min after the sunset)
  • Bottom of water filled body appears to be raised

 

Concave & Convex Lenses

§  Convex Lens – Converging Lenses

§  Power –  Positive

§  Concave Lens – Diverging Lenses

§  Power –  Negative

Power of a lenses  Diopter

 

Dispersion of light

 

Total Internal Reflection

  • Light can not always pass through denser to rarer medium
  • if the angle of incidence > critical angle, it leads to total reflection of light
  • Examples : Optical fiber, Mirage effect (Usually associated with hot deserts)

 

 

Mirage Effect

  • Air near desert surface is hot & which cools rapidly with height (2 different mediums density wise)
  • Rays from top of trees exceeds critical angle & TIR occurs
  • Observer sees tree upside down giving illusion of water
  • Vice a versa if air near the ground is cold & up above hot

 

 

 

Rainbow

  • Formed opposite of sun
  • ProcessRefraction & Dispersion + TIR + Refraction & Dispersion

 

Scattering of Light

  • A molecule of a medium emits incoming light in all possible directions known as scattering (Tyndall Effect)

Blue Color Sky

  • When sunlight reaches earth’s atmosphere, Blue color scatters more strongly than the red
  • When this scattered color enters our eye, sky looks blue to us

Reddish Sunrise / Sunset

  • Light from sun near horizon passes through thicker layers of air & travel larger distances in earth’s atmosphere before reaching our eyes.
  • Blue light & shorter wavelengths scatters away soon letting longer wavelengths of red light reach our eyes

 

Interference of waves

Superimposition of 2 waves of same kind which passes through same point at the same time

  • Constructive interference–   Same phase interference
  • Destructive interference–   Opposite phase interference

Example  Colors in soap bubble & oil on water in presence of white light (Alternate black & white spots in case of monochromatic light)

Diffraction

  • Spreading of light through a narrow slit or aperture
  • Failure of light to travel in a straight line (due to the wave nature of light)

Diffraction Grating A device used to cause diffraction for ex. Parallel equidistant lines on glass or metals (as in CD)

Holograms → Result of Laser + Interference + Diffraction

Fiber Optics & Laser

Fiber Optics & Optical Fibers

§  A technology that uses glass (or plastic) threads (fibers) to transmit data.

§  A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messagesmodulated onto light waves

Fiber optics has several advantages over traditional metal communications lines

§  Much greater bandwidth than metal cables. This means that they can carry more data.

§  Immunity to Electromagnetic Interference

§  Thinner and lighter than metal wires.

§  Data can be transmitted digitally (the natural form for computer data) rather than analogically.

§  Data Security & No sparks hazard

 

Disadvantages of fiber optics

§  Cables are expensive to install

§  More fragile than wire due to limited physical arc of the cable (cannot bend much)

§  Difficult to splice

§  Loss of light in fiber due to scattering

 

Uses 

§  Telecommunications

§  Internal inspection of the body

§  Mechanical imaging

 

LASER

A device that generates an intense beam of coherent monochromatic light (or other electromagnetic radiation) by stimulated emission of photons from excited atoms or molecules. Coherent, in this context, means that it is all one wavelength, unlike ordinary light which showers on us in many wavelengths.

§  Theacronym laser stands for “light amplification by stimulated emission of radiation.

§  Lasers work as a result of resonant effects. The output of a laser is a coherent electromagnetic field.

§  In a coherent beam of electromagnetic energy, all the waves have the same frequency and phase

Lasers are one of the most important inventions of the 20th Century. Here are just a few of applications of Laser

§  Drilling and cutting (To drill holes in diamonds)

§  Alignment and guidance

§  In medicine, such as eye surgery

§  In space exploration  NASA have sent a laser to Mars on their Curiosity Rover.

§  Communication – internet and TV

 

Optical properties of Laser are exploited in

§  Holography

§  Reading barcodes

§  Recording and playing compact discs

 

Bottom of Form

 

Fiber Optics & Optical Fibers

  • A technology that uses glass (or plastic) threads (fibers) to transmit data.
  • A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messagesmodulated onto light waves

Fiber optics has several advantages over traditional metal communications lines

  • Much greater bandwidth than metal cables. This means that they can carry more data.
  • Immunity to Electromagnetic Interference
  • Thinner and lighter than metal wires.
  • Data can be transmitted digitally (the natural form for computer data) rather than analogically.
  • Data Security & No sparks hazard

 

Disadvantages of fiber optics

  • Cables are expensive to install
  • More fragile than wire due to limited physical arc of the cable (cannot bend much)
  • Difficult to splice
  • Loss of light in fiber due to scattering

 

Uses 

  • Telecommunications
  • Internal inspection of the body
  • Mechanical imaging

 

LASER

A device that generates an intense beam of coherent monochromatic light (or other electromagnetic radiation) by stimulated emission of photons from excited atoms or molecules. Coherent, in this context, means that it is all one wavelength, unlike ordinary light which showers on us in many wavelengths.

  • Theacronym laserstands for “light amplification by stimulated emission of radiation.
  • Lasers work as a result of resonant effects. The output of a laser is a coherent electromagnetic field.
  • In a coherent beam of electromagnetic energy, all the waves have the same frequency and phase

Lasers are one of the most important inventions of the 20th Century. Here are just a few of applications of Laser

  • Drilling and cutting (To drill holes in diamonds)
  • Alignment and guidance
  • In medicine, such as eye surgery
  • In space exploration NASA have sent a laser to Mars on their Curiosity Rover.
  • Communication – internet and TV

 

Optical properties of Laser are exploited in

  • Holography
  • Reading barcodes
  • Recording and playing compact discs

 Basics of Mechanics

Equations of motion

V = u + at S = ut + ½ at2 v2 – u2 = 2as

Basic knowledge of Mechanics

  • Circular motion v = (2 (pi) r) / t
  • 0 net force & 0 acceleration does not mean 0 velocity
  • Centripetal force works towards the center = mv2/ r
  • Centrifugal force works wrt revolving body’s frame = Equal & opposite to centripetal force
  • Rolling Friction < Sliding friction
  • Friction is reduced by : Lubricants (as friction b/w Solid & liquid < b/w Solid & Solid), Ball bearings

F= m * a,     Momentum = m * v,   Work = F * distance moved in direction of force

Impulse = f * t = Change in momentum = Small contact time will lead to greater force

Power = WD/Time taken,   K.E = ½ mv2,    P.E = mgh        (Unit of KE & PE = Kwh)

1Kwh = 1000 w * 3600 s = 3600 *1000 J = 3600 Kj

  • Space rockets use liquid fuel + liquid oxygen (i.e. space rockets use its own oxygen to burn the fuel unlike jet engines which draws it from atmosphere)

Gravitational force = GM1M2 / r2     where G = 6.67 * 10-11 unit

Weight of a body is greater at poles than at equator mainly because of 2 reasons

  • Polar radius < Equatorial radius (Hence Greater gravitational force)
  • Greater centrifugal force at equator & 0 at poles

 

Weight of the body wrt Sea level

  • Weight of a body is less at higher elevations than at sea level, due to increase in radius
  • Weight of the body decreases as we move inside the earth & will be 0 at its centre as now gravitational force will act from all the sides
  • Mass of the body will be same everywhere as weight = m * g, hence it is weight that changes
  • Weight of a body at moon is 1/6 of that at earth

Artificial Satellites

r = Distance from centre to earth
mv2 / r  = mg mv2 / r  = GMm/r2
v = (rg)1/2 v = (GM/r)1/2
  • Hence, speed of satellite does not depend on mass of the satellite
  • At a particular distance from the earth, all objects would have same speed of revolution
  • As v is inversely proportional to (r)1/2, when a satellite moves from higher to lower orbit, its speed will increase
  • Velocity of satellite = (6.4 * 106* 9.8)1/2 ~ 8 km/s, Hence if v < 8 km/s, artificial satellite will fall to earth & if it is > 8 km/s, it will have elliptical orbit rather than a circular one
  • Escape velocityIf v > 11.2 km/s, it will escape the earth & would never come back
  • Force of gravity (G) is minimum at equator, hence a better place to launch satellites & that too in west direction as earth moves W E
  • It is even easier to launch satellites from space shuttles due to no gravitational force

 

Geostationary Satellites

  • Satellites whose period of rotation is same as earth i.e. 24 hrs
  • Appears stationary with respect to earth
  • Mainly used for communication & weather forecast

 

Torque = Force * Perpendicular distance (Perpendicular from the line of action of force)

Center of Gravity = A point inside or outside the body where whole weight of the body is considered to act. For ex. Racing cars are built low with wide wheel base to keep COG as low as possible

 

Properties of Solids

Elasticity Material regains shape & size on removal of force
Plasticity Material remains deformed permanently on removal of force
Stress (Restoring force / area)  F / A (Pascal)
Longitudinal strain Change in length / Total length    (in case of tensile & compressive stress)

Hooks law

  • Stress imposed on a solid is directly proportional to the strain produced, within the elastic limit.
  • Stress = k * strain (Where k is modulus of elasticity )

 

Stress Strain Curve

The relationship between the stress and strain that a particular material displays is known as that particular material’s stress–strain curve.

  • It is unique for each material and is found by recording the amount of deformation (strain) at distinct intervals of tensile or compressive loading (stress).
  • These curves reveal many of the properties of a material (including data to establish the Modulus of Elasticity, E)

Stress–strain curves of various materials vary widely, and different tensile tests conducted on the same material yield different results, depending upon the temperature of the specimen and the speed of the loading. It is possible, however, to distinguish some common characteristics among the stress–strain curves of various groups of materials and, on this basis, to divide materials into two broad categories; namely, the ductile materials and the brittle materials

  • Till yield point hooks law is valid & body remains elastic
  • Within yield region (red region), stress & strain are not proportional but body still remains elastic (Known as yield point, Elastic limit & yield strength of the material
  • From yield point to ultimate tensile strength strain increases rapidly even with a small change in stress. Body does not regains its shape & size fully & gets deformed permanently
  • If Ultimate tensile strength & fracture point are closed  Material is brittle & if far away, then the material is ductile

 

Some Basic terms used in properties of solids

Young’s Modulus  (Elastic modulus) A mechanical property of linear elastic solid materialsTensile or Compressive stress / longitudinal strain
Shear modulus (Modulus of rigidity) Shearing stress / shearing strain
Bulk Modulus Used to characterize compressibility of fluids- P/(change in vol. /volume)
Compressibility 1 / bulk modulus

Fluids Mechanics

  • Pressure in liquid (P) = Density * g * h
  • Relative Density (Hg) = 13.6 > Relative Density (Fe)   (Iron flows in mercury & do not sink)
  • Atmosphere exerts pressure on us which is balanced by our blood pressure from inside
  • Nose bleeding occurs at higher altitudes as pressure exerted by our blood exceeds atm. pressure
  • Liquid rises in syringe & straws due to difference in pressure exerted & atm. pressure
  • Atmospheric pressure is measured by Barometer
If barometric height falls suddenly Storm coming
If barometric height falls gradually Possibility of rainfall
If barometric height rises gradually Fair weather
  • Body inside water feels upthrust hence it is easy to lift anything inside water as compared to the land
  • Higher the density of water, greater the upthrust hence it is easier to swim in sea than at swimming pool

Density of Water

  • Density of water = 4*C    Hence, on cooling density of water rises till 4*C & then starts decreasing
  • Density of ice < Density of water
  • Volume of ice > Volume of water
  • Hence, for the same volume of water & ice —- Weight of water > Weight of ice
  • When ice floating in a glass, filled with water, melts then level of water remains same but volume of water decreases

 

Surface Tension

  • Cohesive force b/w liquid molecules that allow it to resist external forces
  • Paint brush dipped in water, all hairs spread & when taken out of water they converge
  • Liquid drops are mainly spherical in shape to have min surface area as for a given volume, sphere has the lowest surface area

 

Capillarity

  • When a clean glass tube is dipped in water, water rises in it as water molecules are attracted to glass more than to each other
  • When the same glass tube is dipped in mercury, level of mercury in glass tube falls below the outside level as mercury molecules are less attracted to glass tube than each other
  • That’s why, a drop of water spread on the glass tube but of mercury remains in spherical shape

Viscosity

  • Fluid friction for liquids & gases (Unit – Pascal second)
  • Viscosity of liquids > Viscosity of gases
  • In liquids, viscosity decreases with increase in temperature, whereas in gases viscosity increases with increase in temperature (Viscosity is independent of pressure)
  • Falling objects gain velocity upto a certain point & then it becomes constant as net force on the object becomes 0 (due to balance by viscous force). This steady velocity is termed as terminal velocity
  • Terminal velocity is higher for heavier & small sized objects

Bernoulli’s Theorem

  • Pressure of fluid decreases with increase in the velocity of fluid (P1V1 =P2V2)
  • Examples include: Sprayers, Spinning of ball, Wings of airplane (V above wings > V below wings & pressure vice a versa)

Heat & Thermodynamics

Thermodynamics

§  (F – 32 / 180 = C/100)  At -40*C both scales show identical readings

§  No upper limit of temp. is defined but have a definite lower limit i.e. absolute 0 k or -273*C

0*C = 237 K 100*C = 373 k Rise of temperature is equal in both the scales

In cold countries we use alcohol in thermometer instead of mercury, because freezing point of mercury is -39*C & of alcohol is -115*C

Electronic Thermometer

§  Basic component thermistor, whose resistance changes with temperature

§  Measures resistance & covert it to temp. as shown digitally

 

Water – Min Volume & Maximum Density at 4*C

§  When temp. falls, top layer of water contracts & become denser & sinks to bottom

§  This process goes on until whole water of the pond reaches 4*C i.e. at max density

§  If temperature falls any further, top layer expands & remain at the top till it freezes and water under it remains at 4*C, leading to survival of aquatic life

 

Heat Transfer Processes

Conduction

§  Occurs in solids, when one end is heated then the other end also heats up

§  Mainly due to transfer of heat though solids particles

 

Convection

§  Occurs in liquids & gases, via circulation of particles to form convectional currents

§  For ex. heating elements in geyser are fitted near bottom & cooling units in freeze are fitted near top

Radiation

§  No medium is required (heating by electromagnetic waves)

§  Good absorbers are good emitters too, for ex : Dark colors & rough surfaces

§  Highly polished surfaces are poor radiators

 

Newton’s law of cooling

§  Rate at which hot body loses heat is directly proportional to surrounding temperature.

§  For ex. a body will come from 90*C to 80*C in less time then 40*C to 30*C

§  Rate of cooling of hot water > rate of cooling of cold water in refrigerator

Cloudy nights are warmer than clear nights as clouds act as a blanket & reflect radiations emitted by earth back to the earth

Specific Heat Capacity

§  Heat required to raise the temperature of a unit mass of substance by 1 k (unit joule/kg*kelvin)

§  Specific heat of water > specific heat of land (1 cal = 4.2 j)

Water is used as a coolant in car engines mixed with ethylene glycol which acts as a lubricant, as a coolant & lowers the freezing point of water

Air conditioner

§  Maintains temperature & humidity of a place

§  1 ton means transfer of 12000 BTU of heat from room in an hour

 

Boiling point of water vs atmospheric pressure

§  Boiling point of water depends on external atmospheric pressure.

§  When atmospheric pressure is at 76 cm of mercury, water boils at 100*C, but when external atm. pressure is increased, boiling point of water is also increased

§  Increased boiling point allow water to hold more heat, which cooks the food faster

§  At higher altitudes, atmospheric pressure is reduced, lowering the boiling point of water & food takes much longer to cook

Electricity & Magnetism

Conductors & Charges

§  When a hollow conductor is charged with static electricity, charge resides on outside surface of the conductor while inner surface remains unchanged.

§  Hence, If a car is struck by lightning, person sitting inside are shielded from electricity & remain unharmed

§  At absolute 0, metals almost reach 0 resistances & become superconductors. for ex. Hg

§   Semiconductors → Electrical conductivity & resistivity is in-between conductors & insulators. For ex. Silicon & Germanium

§  Resistance = Resistivity (length /area) 

§  Resistivity increases with increase in temp. in conductors but decrease with increase in temp. in semi-conductors

 

Electric cells

§  Electrical Cell is a power generating device  Converts stored chemical energy into electrical energy.

§  It is the combination of electrodes & electrolytes, where a difference of certain electric potential is established between the electrodes as a result of the chemical reaction between electrodes & electrolytes.

Based on packaging and shapes, Electrical Cells can can divided into following four categories

Based on the Electrical properties of the cell, Cells can can divided into following four categories

Primary Cell (Dry Cell)

§  An Electrical cell which is powered by the irreversible chemical reaction is called Primary Cell.

§  Since it is powered by irreversible chemical reaction , It cannot be recharged after being used

§  Hence, it can be used only once and need to be disposed off after single use.

§  Most of the primary cell contains their electrolytes in solid form absorbed within some absorbent material so these kind of cells are also called Dry Cell

§  Nickel ion batteries, Lithium batteries zinc–carbon batteries and alkaline batteries etc.

Secondary Cell

§  The Electrical Cell which can be electrically recharged after being used is called secondary cell.

§  These cells are powered by reversible chemical reaction and the state of Electrodes & Electrolyte can be reversed to its original form by applying external power source after being used.

§  Low resistance & provide large current  Lead cells used for ignition & lightening in cars

§  Nickel-Cadmium, Nickel-Zinc ,  Nickel metal hydride,  lithium-ion (Li-ion) cells, lead–acid battery

 

Reserve Cell

§  Cells where one of the key components of the cell is separated from the rest of the components until activated manually or by some automatic means.

§  These kinds of cell remain deactivated and nonfunctional until it is activated manually or by some means like heat, water or other means.

One example is thermal cell (Photovoltaic) where the electrolyte remains inactive in its solid form until the heat applied melts the electrolSection 2 → Chemistry articles for Civil Services Preparation

§  yte to activate the cell.

Fuel Cell

§  A Fuel Cell is the kind of cell where the chemical energy from a fuel fed into the cell is converted into electrical energy through a chemical reaction with oxidizing agent.

§  The fuel that is fed into a fuel cell can be Hydrogen, Hydrocarbons, Natural gas etc.

§  A fuel cell can produce electricity as long as the fuel and the oxidizing agent are fed into the fuel cell.

Battery

§  A single unit of electro-chemical generator is known as Electrical Cell, while the combination of several such units connected electrically is known as a Battery.

§  Several cells are combined and connected electrically in series or parallel to form a battery which has two main terminal electrodes one Positive and one Negative.

§  The electrical potential difference between the two main electrodes depends upon the numbers of cells, types of cells and the types of combination used to form the battery.

 

Some Basic terms used in electricity

Dynamo / Electric Generator Converts mechanical energy into electrical energy
Invertor Converts DC  AC
Filament Lamp Tungsten filament filled with argon gas (Highly heat producing  Wastage)
Fluorescent Tubes Mercury vapours filled at low pressure (Lower heat producing)
Motor  Current carrying conductor when placed at right angle to the magnetic field, undergoes motion due to electromagnetic forceCoverts electric energy into mechanical energy
Fuse   A thin wire of tin-lead alloy with low melting pointNow days substituted by MCB – Miniature circuit board
3 Pin Plug   Top Bigger Hole (Earth)  — Earthed 1st before connecting to live circuitLeft Hole (Neutral)Right Hole (Live)
Cables   Red / Brown (Live wire);   Blue / Black (Neutral);   Green / Yellow (Earth)All the switches in house are put at live wire, if they were put in neutral wire, sockets would remain live even after switches are in off position & person will get sock

 

Modern Physics

Model of an atom

Protons Discovered by Goldstein  Neutrons > Protons > Electrons  (in terms of mass) 
Electrons Discovered by Thomson
Neutrons Discovered by Chadwick

Radioactivity

§  When size of nucleus enlarges  Electrostatic force > Nuclear force, which leads to radioactivity

§  Unstable atomic nuclei will spontaneously decompose to form nuclei with a higher stability.

§  The decomposition process is called radioactivity. The energy and particles which are released during the decomposition process are called radiation.

§  When the unstable nuclei are prepared in the laboratory, the decomposition is called induced radioactivity.

§  When unstable nuclei decompose in nature, the process is referred to as natural radioactivity.

Three major types of natural radioactivity

Alpha radiation

§  Consists of a stream of positively charged particles, called alpha particles

§  Alpha particles have an atomic mass of 4 and a charge of +2 (a helium nucleus).

§  When an alpha particle is ejected from a nucleus, the mass number of the nucleus decreases by four units and the atomic number decreases by two units. For example:

 

23892U → 42He + 23490Th        (The helium nucleus is the alpha particle)

 

Beta Radiation

§  Consists of a stream of electrons, called beta particles.

§  When a beta particle is ejected, a neutron in the nucleus is converted to a proton, so the mass number of the nucleus is unchanged, but the atomic number increases by one unit. For example:

 

23490Th    → 0-1e + 23491Pa (The electron is the beta particle)

 

 Gamma Radiation

§  Gamma rays are high-energy photons with a very short wavelength (0.0005 to 0.1 nm).

§  The emission of gamma radiation results from an energy change within the atomic nucleus.

§  Gamma emission changes neither the atomic number nor the atomic mass.

§  Alpha and beta emission are often accompanied by gamma emission, as an excited nucleus drops to a lower and more stable energy state.

 

Applications of Radioactivity

§  Used as a tracer for chemical reactions. You can put an isotope in a living organism and it will do the same reactions as the regular element but you will be able to trace what it reacts with and where it goes

§  Detecting how old something is by seeing how much of the isotope of the element is left  Carbon Dating   C 14 (Used for living organisms) & Uranium dating   For non-living organism ex. rocks

§  Used for finding out the faults in metal structures esp. in airplanes  radioactive material will penetrate more through the cracked areas

§  Act as a fuel for nuclear reactors to produce electricity

§  Some isotopes are used in the treatment of cancer to kill the cancer mutated cells

§  Some isotopes are used to study the proper functioning of internal organs

§  Gamma radiations are used to sterilize the surgical instruments

§  Radio phosphorous is used for studying the rate of phosphorous assimilation by the plant

§  Preservation of food grains and seeds

§  Used for preparing synthetic elements (artificial transmutation)

§  Detecting leaks in natural gas pipes

 

Nuclear fission

§  In nuclear fission the nucleus of an atom breaks up into two lighter nuclei.

§  The process is accompanied by the release of a large amount of energy.

§  The process may take place spontaneously in some cases or may be induced by the excitation of the nucleus with a variety of particles (e.g., neutrons, protons, deuterons, or alpha particles) or with electromagnetic radiation in the form of gamma rays.

 

Atomic bomb → Only by fissile U 235 i.e. Enriched Uranium (90%)

For Nuclear reactors  6 % of U-235

 

 

Nuclear fusion

§  Process by which nuclear reactions between light elements form heavier elements (up to iron).

§  During this process, matter is not conserved because some of the matter of the fusing nuclei is converted to photons (energy)  substantial amounts of energy are released.

 

 

Hydrogen bomb  Requires an atomic bomb to detonate

 

 

Nuclear Reactor

§  A nuclear reactor, formerly known as atomic pile, is a device used to initiate and control a sustained nuclear chain reaction.

§  Nuclear reactors are used at nuclear power plants for electricity generation and in propulsion of ships.

§  Heat from nuclear fission is passed to a working fluid (water or gas), which runs through turbines.

§  These either drive a ship’s propellers or turn electrical generators.

Sequential Process

Fission Controlled chain reaction of U 235 or Plutonium 239
Moderators D2O, H2O, Solid Graphite (To slow down neutrons bombardment & start a chain reaction)
Heat Generation  Rotation of turbines  Powering Generator  Electricity through cable lines
Cooling Liquid sodium
Control Rods Cadmium (Which absorb excess neutrons)

 

Space & Astronomical Science

1 Light yr    9.46  * 10^15 m 1 AU            1.495 * 10^11 m
Earth to Moon Distance  3.84 * 10^ 8 m Earth to Sun Distance  1.495 * 10^11 m
Astronomical unit  The mean distance from the centre of the earth to the centre of the sun

Galaxies

Galaxies are huge collections of stars, dust and gas. They usually contain several million to over a trillion stars and can range in size from a few thousand to several hundred thousand light-years across.

§  There are hundreds of billions of galaxies in the Universe.

§  Galaxies come in many different sizes, shapes and brightness

§  Like stars, are found alone, in pairs, or in larger groups called clusters.

§  Galaxies are divided into three basic types: spiral, elliptical and irregulars.

§  Our solar-system is part of galaxy called ‘Milky-Way.

 

Doppler Effect & Expanding Universe

§  When the distance between the source and receiver of electromagnetic waves remains constant, the frequency waves is the same in both places.

§  When the distance between the source and receiver of electromagnetic waves is increasing, the frequency of the received wave forms is lower than the frequency of the source wave form.

§  When the distance is decreasing, the frequency of the received wave form will be higher than the source wave form.

 

If a body in space is “blue shifted,” its light waves are compacted and it is coming towards us. If it is “red shifted” the light waves are spread apart, and it is traveling away from us. All the stars that we have detected are “red shifted,” which is one piece of evidence for the theory that the universe is constantly expanding, perhaps from a “big bang.”

Nebula

A nebula is a cloud of gas and dust in space. Some nebulae (more than one nebula) are regions where new stars are being formed, while others are the remains of dead or dying stars.

§  The word nebula comes from the Latin word for cloud

§  Nebulae come in many different shapes and sizes.

 

There are four main types of nebulae

§  Planetary nebulae

§  Reflection nebulae

§  Emission nebulae

§  Absorption nebulae

 

Constellations

A constellation is a group of stars that make an imaginary shape in the night sky hence constellations are not real. They are usually named after mythological characters, people, animals and objects.

§  In different parts of the world, people have made up different shapes out of the same groups of bright stars. It is like a game of connecting the dots.

§  In the past creating imaginary images out of stars became useful for navigating at night and for keeping track of the seasons.

§  Because all the stars are at different distances, the constellations would look totally different to inhabitants of another planet orbiting another star.

 

Major Constellations

§  Ursa Major (Great Bear)

§  Orion (Giant hunter)

§  Hydra (Sea Serpent)  Largest

§  Cygnus (Swan)

§  Hercules

§  Centaurus

 

Stars

§  Stars are big exploding balls of gas, mostly hydrogen and helium.

§  Our nearest star, the Sun, is so hot that the huge amount of hydrogen in it is undergoing a constant star-wide nuclear reaction, like in a hydrogen bomb.

§  Even though it is constantly exploding in a nuclear reaction, the Sun and other stars are so large and have so much matter in them that it will take billions of years for the explosion to use all the “fuel” in the star.

§  After a star runs out of fuel, it ejects much of its material back into space.

§  New stars are formed from this material. So the material in stars is recycled.

Death of a star

When a star begins to exhaust its hydrogen supply, its life nears an end. The first sign of a star’s old age is a swelling and reddening of its outer regions. Such an aging, swollen star is called a red giant.

For Big stars when fuel (hydrogen) in its core runs out, it starts contracting, resulting in fusion of successive heavier nuclei like helium, carbon, oxygen etc. till a stage is reached when there is mostly iron & no more fusion takes place.

Supernova  This collapsing core imparts so much energy to the exterior of the star that it explodes with an increase in its luminosity 10000 times or even more

White dwarf  After the explosion the highly dense residual core of comparatively small star (mass upto 1.4 times our sun – Chandrashekhar limit)

The extremely dense core left after the explosion of a bigger star is called as Neuron star (mass upto 1.4 – 3 times our sun). Due to its small size, they spin very fast & radiate all kind of electromagnetic radiations. When this happens the star is known as Pulsar.

Black Holes

Still bigger stars with left core mass (after explosion) greater than 5 times the sun (most dense form) are believed to end up as black holes.

§  It is extremely concentrated matter.

§  The pull of gravity is so powerful that nothing, not even light, can emerge from it (hence can’t be seen)

§  Black-hole formation indicates ultimate death of a star.

 

How Sun will End its life

The star collapses under the force of its own weight; if it is a small star, it collapses gently and remains collapsed. Such a collapsed star, at its life’s end, is called a white dwarf.

§  The Sun will probably end its life in this way.

§  The Sun, a middle-aged star, will probably swell to a red giant in 5 billion years, vaporizing Earth and any creatures that may be on its surface.

 

Solar System

§  Our solar system consists of Sun + 8 Planets + 1 Dwarf planet (Pluto) + No. of Natural Satellites

§  Pluto was demoted to dwarf planet at 26th general assembly of International Astronomical Union held at Czech republic in 2006

§  Only sun has its own light, which is also the nearest star to the earth

Size – Wise Jupiter > Saturn > Uranus > Neptune > Earth > Venus >Mars > Mercury
Inner / Terrestrial Planets Earth, Venus, Mars, Mercury
Jovian / Outer Planets Jupiter, Saturn, Neptune, Uranus
No. of Satellites Jupiter (63) > Saturn (60) > Uranus (27) > Neptune (13) > Mars (2) > Earth (1) > Venus (0) & Mercury (0)   (Moon at Jupiter were found by Galileo)
Time Period of revolution of Planets around the sun Neptune > Uranus > Saturn > Jupiter > Mars > Earth > Venus > Mercury (88 days)

§  Asteroids – A belt of minor planets revolving around the sun between Mars & Jupiter

§  All Planets revolve west to east around the sun except Uranus & Venus which moves east to west around the sun (Retrograde motion)

§  A ray of light from sun takes about 8 mins 17 secs to reach the earth. Light takes about 1 second to reach us from the moon.

Uranus Maximum inclination of 98* towards the sun  known as lopsided planet
Earth §  Inclination of 23.5

§  Blue planet due to presence of water (Approx. 71% area)

Mercury No inclination at all
Venus §  Hottest planet  due to total absence of atmosphere at Mercury

§  Earth’s twin because of their close proximity in size, mass & density

Mars §  Red planet due to presence of Feo (Iron oxide) dust

§  Named after roman god of war

§  Believed to have the possibility of some plant life

Jupiter Distinguished from other planets by a circular light & dark bands
Saturn Planet with three rings around it

Sun

§  Sun is the only star in our Solar System as it has its own source of light and energy.

§  Mass of the Sun accounts to 99.86% of our Solar System.

§  Its average distance from the Earth is around 149,600,000 km.

§  Sunlight takes about 8 min 17 secs to reach the Earth.

§  Sun’s energy is produced by constant nuclear fusion in its core through a series of processes called the p-p (proton-proton) chain. This process converts Hydrogen into Helium.

 

Composition of sun 

§  Hydrogen    74.9%

§  Helium        23.8%

§  Metals         1.3%

 

Structure of Sun

The structure of the Sun can be divided into several different layers as follows:

Core

§  The core of the Sun has the highest temperature and pressure among all layers.

§  The temperature of the core is around 15 million degree Celsius – is in ionized state called plasma

§  The solar energy is produced in the core by controlled nuclear fusion process.

§  The high temperature in the core helps in removing the electrons from hydrogen atoms and in creating numerous electrons and protons for nuclear fusion.

 

Radiative Zone

§  The Sun’s radiative zone is the section of the solar interior between the innermost core and the outer convective zone.

§  In the radiative zone, energy generated by nuclear fusion in the core moves outward as electromagnetic radiation.

 

Convective zone

§  In this zone the density of plasma is low.

§  This zone transports hot and light density fluids from the core region of high energy & temperature to the outer region of low energy & temperature.

 

Photosphere

§  This is the first visible layer of the Sun.

§  The temperature here is around 6000 degree Kelvin (5370 degree Celsius).

§  The solar spots are formed on this layer. The temperature of a solar spot is around 4500 degrees.

Solar spots  Temporary dark spots formed when the magnetic field bursts through the surface. It can slow down the flow of energy from the inside of the Sun – that’s what makes the sun spots cooler & darker than the surrounding photosphere.

Chromosphere

§  Chromosphere literally mean as ‘sphere of colour’.

§  This layer is dominated by emission lines.

 

Corona

§  This is the outermost layer of the Sun.

§  High temperature in this region gives it an unusual spectral feature of a highly ionised ion.

§  Chromosphere & corona are visible only during formation of Diamond Ring during Solar eclipse.

 

Some Generic Space Terms

Asteroid A celestial body bigger than 10 m orbiting the Sun, mainly between Mars and JupiterMade of rock and metal, they can also contain organic compounds.Are similar to comets but do not have a visible coma (fuzzy outline and tail) like comets do
Meteoroid A meteoroid is a small rock or particle of debris in our solar system. They range in size from dust to around 10 metres in diameter (larger objects are usually referred to as asteroids).
Meteor A meteoroid that burns up as it passes through the Earth’s atmosphere is known as a meteor. If you’ve ever looked up at the sky at night and seen a streak of light or ‘shooting star’ what you are actually seeing is a meteor.
Fireball A very bright meteor (brighter than the planet Venus).
Bolide A fireball that explodes during its atmospheric flight, often with visible fragmentation.
Meteorite The part of a meteoroid or asteroid that survives the passage through our atmosphere and reaches the Earth’s surface.
Comet A smaller celestial body mainly composed of ice, rock and dust. As comets travel close to the Sun, some of the ice melts off and becomes a gas. This melting process causes bits of dust and debris to trail behind the comet. This tail can be seen in the night sky as a bright, quickly-moving light

 

Halley’s Comet

§  Halley’s Comet is arguably the most famous comet.

§  It is a “periodic” comet and returns to Earth’s vicinity about every 75 years, making it possible for a human to see it twice in his or her lifetime.

§  The last time it was here was in 1986, and it is projected to return in 2061.

The comet is named after English astronomer Edmond Halley, who examined reports of a comet approaching Earth in 1531, 1607 and 1682. He concluded that these three comets were actually the same comet returning over and over again, and predicted the comet would come again in 1758.

Cern & Higgs Boson particle

Standard model

§  a theory of Particle Physics, which says all the material around us is made up of 12 matter particle (Fermions)

§  11 particles predicted by the model have been found and only Higgs particle was not yet found, so the CERN was trying to find it.

 

Higgs Boson particle

§  theoretically responsible for mass, without which there would be no gravity & no universe hence named God Particle

§  was proposed in the 1960s by British physicist Peter Higgs as a way of explaining why other particles have mass

Big Bang & Universe Formation

§  Big Bang occurred approximately 13.75 billion years ago, responsible for the creation of Universe

§  But after the Big Bang, the universe was a gigantic soup of particles racing around at the speed of light without any mass to speak of

§  It was through their interaction with the Higgs field that they gained mass and eventually formed the universe

§  Thus finding the Higgs particle can throw more light on how universe was formed

 

European Organization for Nuclear Research (CERN)

§  situated at Geneva, along France-Swiss border,

§  operating several particle accelerators the latest one being Large Hadron collider

 

Large Hadron collider (LHC)

§  world’s biggest and most powerful particle accelerator

§  Two beams of protons are fired in opposite directions around it before smashing into each other to create many millions of particle collisions every second

 

Above stated process is an attempt to recreate the conditions which could have occurred, a fraction of a second after the Big Bang, when the Higgs field is believed to have ‘switched on’ and did the magic

CERN scientists discovered two subatomic particles belonging to the family of baryon

§  six times as massive as protons

§  made up of 3 strongly-bound elementary particles called quarks like protons

§  heavy weight due to their spins in opposite directions in which their quarks configure

 

Centre’s nod for India’s associate membership in CERN

Currently, India has observer status in CERN, which has 21 member states. The status of associate member is also the pre-stage to full membership.

§  To be an associate member, India will have to pay $10.7 million annually.

§  As an associate member, India would be entitled to attend restricted sessions of the organization

§  Allow Indian industry to participate in bids for Cern contracts across various sectors

 

Trivia

§  Israel is the first (and currently only) non-European country granted full membership.

§  CERN is also the place the World Wide Web was first implemented.

 

Forces found in nature

§  Strong Nuclear force (Short range force)

§  Electromagnetic force (Short range force)

§  Weak Nuclear force   (Short range force)

§  Gravitational force      (Short range force)

 

Order → Strong Nuclear Force > Electromagnetic Force > Weak Nuclear Force > Gravitational Force

 

Section 2 → Chemistry articles for Civil Services Preparation

Properties of Matter

  • Matter is anything, such as a solid, liquid or gas that has weight (mass) and occupies space.
  • For anything to occupy space, it must have volume viz. everything on earth is matter

 

Properties of Matter

  • All properties of matter are either physical or chemical
  • Physical properties can be measured without changing a substance’s chemical identity
  • Chemical properties can be measured only by changing a substance’s chemical identity

 

  • Physical properties are further divided into intensive or extensive
  • Extensive properties, such as mass and volume, depend on the amount of matter being measured.
  • Intensive properties, such as density and color, do not depend on the amount of the substance present.
Physical Properties 

§  Colour

§  Density

§  Volume

§  Mass

§  Odour

§  Density

§  Hardness

§  Ductility

§  Malleability

§  Conductivity

§  Solubility

§  Boiling Point

§  Melting Point

Chemical Properties 

§  Paper burns

§  Iron rusts + Gold does not rust

§  Wood rots

§  Nitrogen does not burn

§  Silver does not react with water

§  Sodium reacts with water

 

In each of these, the substance’s chemical property is its tendency to:

§  React (Oxidation / Reduction)

§  Tarnish

§  Corrode

§  Explode

 

States of Matter

Solids

  • Are tightly packed, usually in a regular pattern
  • Incompressible + fixed volume + Fixed shape
  • Solid particles vibrate (jiggle) but generally do not move from place to place

 

Liquids

  • Liquids are close together with no regular arrangement
  • Incompressible – No fixed shape but definite volume
  • Liquids vibrate, move about, and slide past each other.
  • Assumes the shape of the part of the container which it occupies

Gases

  • Are well separated with no regular arrangement
  • Highly compressible – No fixed Shape or volume
  • Vibrate and move freely at high speeds.
  • Assumes the shape and volume of its container

 

Plasma

  • Occurs at high temp. & low pressure
  • Atoms break into ions & free electrons, Forms a glowing state e.g. Inside sun / stars
  • Consists of highly charged particles with extremely high kinetic energy
  • Gases in neon sign board   fluorescent tube ionize to form plasma when electricity is passed through them

 

Bose Einstein condensate

  • Occurs on cooling an atom of very low density at very low temp.
  • Using a combination of lasers and magnets, Eric Cornell and Carl Weiman cooled a sample of rubidium to within a few degrees of absolute zero.
  • At this extremely low temperature, molecular motion comes very close to stopping altogether.
  • Since there is almost no kinetic energy being transferred from one atom to another, the atoms begin to clump together.
  • There are no longer thousands of separate atoms, just one “super atom.”
  • Least energy among all five states

 

BEC is used to study quantum mechanics on a macroscopic level. Light appears to slow down as it passes through a BEC, allowing study of the particle/wave paradox. A BEC also has many of the properties of a superfluid — flowing without friction.

Mixtures, Solutions & Chemical Processes

All matter can be broken down into two categories viz. pure substances and mixtures

  • A pure substance is any matter that always has the same composition or “make up”.
  • There are 2 classifications of pure substances: elements and compounds.
  • An element is a substance that cannot be broken down into simpler substances. An element is made up of only one type of atom.
  • A compound is a substance that is made up of 2 or simpler substances.

 

  • A mixture is a combination of 2 or more substances “non-chemically”.
  • This means we can separate a mixture without undergoing a chemical reaction or chemical change.
  • All mixtures can be classified into 2 groups: homogeneous and heterogeneous.
  • Homogeneous Mixture  (Solvent + Solute) not distinguished. for ex. solution & colloids
  • Heterogeneous Mixture  (Solvent + Solute) readily distinguished. for ex. suspension mixture

 

Separation Methods of Mixtures

For 2 Solids 

§  Suitable solvent

§  Sublimation

§  Magnet Use

For 2 Liquids 

§  Fractional Distillation (For miscible liquids)

§  Separating Funnel (For immiscible liquids) 

For Solids & Liquids  §  Filtration

§  Centrifugation

§  Evaporation

§  Crystallization  (Slow Cooling)

§  Distillation

§  Chromatography  (For different solubility solutes, esp. used in forensic science)

 

Difference between Mixture & Compound

Mixture Compound
§  Can be separated by physical methods (Filtration, Distillation)

§  Exhibit properties of its constituents

§  No energy change takes place

§  Variable composition

§  Can be separated by chemical methods

§  Exhibit different properties of its constituents

§  Fixed Composition

§  Energy change takes place

 

Solution, Suspension & Colloids

Solution

  • Homogeneous mixture with particle size < 1 nm diameter
  • Does not separate out on keeping still & cannot be separated by filtration
  • Does not scatter light due to extremely small particles
  • Examples include: Carbonated drinks, Salt & Sugar solution

 

Colloids

  • Heterogeneous but appears homogeneous with particle size b/w 1 – 100 nm in diameter
  • Does not separate out on keeping still
  • Separates out on centrifugation, not by filtration
  • Scatters a beam of light – Tyndall Effect
  • include Milk, Blood, Soap solution, Ink, Jelly, Starch solutions, Body lotions, Foam, Gels, Gemstones etc.

 

Suspension

  • Heterogeneous mixture with particle size > 100 nm in diameter
  • Particles settle down on keeping still & separates out by filtration
  • Scatters a beam of light with particles of the solute seen easily.
  • Examples include: Sand in water, Milk of magnesia, Chalk solution in water

 

Solubility

  • Maximum quantity of solute in 100 gm of solvent at a particular temperature
  • Increases on increasing the temperature in liquids ( Decreases in case of gas)
  • No effect of pressure in liquids (solubility increases in case of gases on increasing pressure) 
  • Saturated Solution → No more solute can be dissolved without increasing temperature
  • Unsaturated Solution → More solute can be dissolved without increasing temperature

 

Important Chemical Processes

Diffusion

  • Spreading & mixing of one substance with the another due to the motion of particles, which continues till a uniform mixture is formed
  • Mixing particles move in zigzag known as Brownian motion
  • Increases with temperature, fastest in gases & slowest in solids
  • Few of the examples are : Dust particles in air, Smell of perfume in air, Spread of virus on sneezing, CO2 & O2 in water, Leakage of LPG (Identified by ethyl merceptane – a strong smelling substance)

 

Osmosis

  • Diffusion is the case of using semi permeable membrane b/w 2 mixtures
  • Only solvent is allowed to pass, from higher solvent conc. to the lower
  • Few of the examples are:
  • Preserving of pickle in salt
  • Swelling up of raisins in water
  • Earthworm dying when come in contact with salt

 

Dialysis

  • Same as osmosis but for transplantation of kidney in humans
  • Passes solvent & blocks waste

 

Latent Heat

  • To change the state of a substance from one to heat energy is required.
  • Latent heat does not increase temp. of a substance but is used in overcoming force of attraction b/w particle of a substance

It’s due to loss of latent heat that ice at 0*C is more effective in cooling than water at 0*C & due to gain of latent heat that steam at 100*C causes more severe burns than water at 100*C

 

Evaporation

  • Transition of liquid to vapour at normal temperature
  • Causes cooling when liquid evaporate as it draws latent heat of vaporisation from the liquid
  • For ex. evaporation of ether or spirit from our hand, sweating, water kept in earthen pot
  • Increases with temp, large surface area, wind speed & low humidity

 

Sublimation

  • Transition of solids directly into gases without going through liquid state
  • Ex: Dry ice, Camphor, Ammonium chloride, Iodine, Naphthalene, Anthracene

Atoms and Molecules

Structure of an Atom

  • Matter has mass and takes up space. Atoms are basic building blocks of matter, and cannot be chemically subdivided by ordinary means.
  • Atoms are composed of three types of particles viz. protons, neutrons, and electron.
  • Mainly protons and neutrons are responsible for most of the atomic mass
  • The nucleus of an atom consists of protons (each with a positive charge +1) and neutrons (zero charge).
  • The electrons orbit round the nucleus, each with a negative charge of -1.
  • A stable atom has the same number of electrons orbiting as it does protons in the nucleus; this makes the atom electrically neutral.

 

Name Charge Location Mass Discovery
Proton +1 Atomic nucleus 1.6726 X 10-27 kg Goldstein
Neutron 0 Atomic nucleus 1.6750 X 10-27 kg Chadwick
Electron -1 Electron orbital 9.1095 X 10-31 kg Thomson

 

  • Atomic Number (Z) → Number of Protons (or of electrons) in an atom of an element
  • Mass Number (A)    → {Number of Protons (or Electrons) + Number of Neutrons} in an atom of an element
  • Atomic or Molecular Mass → of times one atom or molecule of substance is heavier than 1/12 of carbon atoms 
  • Mass of 1 ‘C’ atom = 12 u where    u = 1.66 * 10^ -24
  • No. of electrons outer shells – 2n^2

 

Elements, Molecules & Compounds

Element

  • It is a substance that cannot be further resolved into simpler substances by chemical means.
  • Itis a substance that is made entirely from one type of atom.
  • For ex. Hydrogen, Carbon, Gold etc.

 

Compound

  • It is a substance made of more than one type of atoms.
  • It is a substance made from two or more different elements that have been chemically joined
  • For ex. H2O), NaCl, CaCO3

 

Molecules

  • This is the smallest unit of a compound.
  • A molecule is formed when two or moreatoms join together chemically.
  • All compounds are molecules but not all molecules are compounds.
  • Molecularhydrogen (H2), molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element.
  • Water (H2O), carbon dioxide (CO2) and methane (CH4) are compounds because each is made from more than one element

 

Valence Electrons

Atoms that are missing an electron (that is, have one more proton than electrons) will tend to attract additional electrons, while atoms that have an excess electron (one more electron than protons) will tend to eject the outer-most electron.

  • The shell containing the outer-most electron is called the valence shell, and is the chemically active shell.
  • Electrons present in outer shell, taking part in a chemical reaction to fulfill outermost shell are known as valence electrons
  • Valency → Number of valence electrons required or donated to fulfill outermost shell

 

Covalency §  Formed between two non-metals that have similar electronegativity

§  Low Melting & Boiling Points

§  Does not conduct electricity

§  Soluble in organic solvents

§  Liquid or gaseous at room temperature

Electrovalency §  Formed between a metal and a non-metal

§  High Melting & Boiling Points

§  Conducts electricity

§  Soluble in water, not inorganic solvent

§  Solid at room temperature

 

Isotopes

  • Atoms with the same number of number of protons & electrons but different number of neutrons
  •  Hence, same atomic number but different atomic mass

 

  • By changing the number of neutrons, isotopes still maintain the same overall neutrality and hence the chemical behavior remains unchange
  • Hence same chemical properties but different physical properties

 

  • Examples include – Protium (1H), Deutirium (2H) & Tritium (3H)
  • Tritium is used in thermonuclear devices + also acts as a tracer

 

Radioactive decay

  • Some isotopes are unstable, especially those with a lot of neutrons compare with the number of protons in the nucleus.
  • These isotopes tend to eject some particles, in the form ofradiation, until a stable nucleus is produced.
  • Such ejection process is called theradioactive decay.
  • Isotopes that undergo radioactive decay are calledradioisotopes or radionuclides.

 

Radioactive Isotopes
Uranium Dating – For non-carbon containing materials Serves as fuel for nuclear reactors for Ex. U -235
Radiodating – C 14 (For carbon containing materials) Goiter Treatment – Radiaoactive Iodine
Nuclear Bombs – U 235 & Plutonium 239 To Detect Tumors – Arsenic 74
To detect blood clot – Sodium 24 Cancer treatment (Radiotherapy) – Co 60, Radon

 

Half life

  • A unit used to measure the stability of a radioisotope
  • It is the time taken for half of the radioisotope in a sample to undergo radioactive decay
  • Stable radioisotopes may take years to decay while the unstable ones may disappear in fractions of a second

 

Isobars

  • Same mass number but different atomic number
  • Different number of protons (or electrons) but same number of neutrons + protons in the nucleus
  • Examples  40Ar18 & 40Ca20

 

Isodiapheres

  • Same difference between (Neutrons – Protons) b/w two elements

 

Metals, Non Metals, Acids and Bases

Metals

  • Malleable, Ductile & Good conductor of electricity
  • High melting & boiling points (Except Na & K)
  • Lustrous, Hard (Except Na & K) & Solid at room temp. (Except Hg)
  • Forms cations or positive ions for ex. lithium batteries as used in cell phones

 

Metalloids

  • Have some properties of metal & some of non-metals
  • For ex. Boron, Silicon, Germanium

Non Metals

  • Forms anions except NH3+ & H+
  • Iodine is a non-metal but lustrous
  • Diamond – Purest form of carbon, hardest natural substance, good conductor of heat
  • Graphite – Good conductor of electricity (used in electrodes)

 

Acids & Indicator Dyes

Acids

Forms H+ ion in presence of water Reacts with metals to form Hydrogen
Reacts with bases to form salt & water Sour taste, Ph < 7
Citric Acid – Lemon, Orange Acetic Acid – Vinegar
Lactic acid – Sour milk, Curd Tartaric acid – Tamarind, Raw grapes
Oxalic acid – Tomatoes Formic acid – Ant sting, Nettle leaf sting

Indicators – Dyes which give different colors in acids and bases

Indicator Color in Acid Color in Base Color
Litmus Red Blue Purple
Red Cabbage Red Green Red
Methyl orange Red Yellow Orange
Turmeric Yellow Red Yellow
Phenolphthalein Colorless Pink Colorless

 

Olfactory Indicators – Based on Smell

  • Vanilla – No smell in presence of a base but natural smell in presence of an acid
  • Onion – No smell in presence of a base but natural smell in presence of an acid

 

Type of Reactions

Exothermic Reactions    §  Heat producing reactions

§  All combustion reactions

Endothermic Reactions §  Heat absorbing reactions

§  All decomposition reactions

Oxidation Reaction §  Addition of O2 or removal of H2

§  Rusting of iron– Formation of Feo (aq.) + Fe2O3

Reduction Reaction §  Removal of O2 or addition of H2

§  For Ex. Vegetable oil → Vanaspati ghee

Rancity foul smell on oxidation of food material prepared in oil or ghee, when left in open for a long time
Matters can neither be created nor destroyed in a chemical reaction i.e. no. of atoms on LHS = no. of atoms on RHS

 

Important Acids and Bases

Nitric Acid §  Used in the formation of TNT & RDX (Nitroamine, Cyclonite)
Gastric Juice §  An acidic digestive fluid (containing HCl), secreted by glands in mucus membrane in stomach

§  Formed due to overeating or emotional factors (too much HCl produced)

Antacids §  Acid inhibitors help to control hyperacidity

§  Examples include Mg(OH)2, CaCO3, NaHCO3 etc. which finally forms CO2 , & comes out as we Belch

Amphoteric Oxides §  Oxides showing basic as well as acidic nature

§  For ex. Al oxide, Zn oxide

Aqua Regia §  HNO3 + 3HCl

§  Dissolves all metals even gold & platinum

K, Na & Li §  Very reactive metals & reacts vigorously with O2 in presence of air

§  Hence are kept under Kerosene oil

CaCO3 §  Used in toothpaste & chewing gum
Sodium  §  Used for making tetraethyl or tetramethyl lead (Antiknocking agents)

§  Liquid sodium is used as a coolant in nuclear reactors

NH3 + §  Used as refrigerant

Alloys, Hardness of Water & Important Chemical Compounds

Alloys

Stainless steel Fe + Cr + Ni
Brass Cu (80 %) + Zn (20 %)   (Golden in Color)
Bronze Cu (90 %) + Sn (10 %)
Solder Pb (50 %) + Sn (50 %)
Steel Fe + C
Magnalium Al + Mg
Amalgam Hg + Ag + Sn + Zn  (used by dentists to fill teeth)
Duralium Al + Mg + Cu + Mn (making aircrafts, satellites & kitchenware)

 

Hardness of Water

Soft  Water §  Produces leather with soap readily
Hard Water §  Does not produce leather with soap readily

§  Due to the presence of bicarbonates, sulphates & chlorides of “Calcium & Magnesium”

 

Temporary Hardness Due to the presence of bicarbonates which can be removed easily by boiling & filtering
Permanent Hardness Due to the presence of sulphates & chlorides which cannot be removed by simply boiling water
Heavy Water Deuterium oxide (D2O) – Used as a moderator

 

Important Chemical Compounds

Cao (Quick Lime)  §  Used for white wash of houses after diluting with water i.e. Ca (OH)2 or slacked lime

§  Also used in glass & cement manufacturing

§  Used in purification of sugar

Washing Soda (Na2CO3.10H2O)  §  Used as detergent (Have cleaning properties)

§  Na2CO3 anhydrous is known as Fly Ash

§  Removes permanent hardness of water

§  Used to make Borax

Bleaching Powder (CaOCl2)  §  Also known as chlorides of lime

§  Bleaching agent in CaOCl2 is chlorine (makes colored substance colorless)

§  Used in disinfecting water supply, bleaching cotton & in paper industry

Baking Soda (NaHCO3)  §  Used for faster cooking of food & baking cakes, breads etc.

§  Used as Fire extinguishers (H2SO4 + NaHCO3 à CO2, which cuts oxygen supply)

§  Also used as antacid

Plaster of Paris (CaSO4.1/2H2O)  §  Made by heating gypsum (CaSO4.2H2O)

§  Used in Plasters, fire proofing, wall smoothening, Making chalks &  Statues

Soap §  Na & K salt of long chain of fatty acids (carboxylic acid)

§  Na salts – Hard soaps,    K Salts – Soft soaps (Shaving foam & shampoo)

§  Basic in nature

§  On adding common salt, solubility of soap decreases in water (Salting out)

Detergent §  Na salt of long chain of benzene sulphonic acid or alkyl hydrogen sulphate

§  Used for washing even with hard water

 

Important Chemical Compounds – Colours

White Vitriol Zinc Sulphate
Blue Vitriol Copper sulphate (Aq)
Green Vitriol Ferrous Sulphate
Wolfram Tungeston
Super Halogen Fluorine
Plastic Sulphur Allotrope of sulphur (super cooled liquid)
Chlorine – Yellowish Green Graphite – Black
Sulphur – Yellow Bromine – Reddish Brown
Phosphorus Red, White & Black (White – Most Reactive)

Environmental Chemistry & Fractional Distillation of Crude Oil

Environmental Chemistry

SO2 §  Produced when sulfur containing fossil fuel is burned

§  Effects – Irritation in eyes, Stiffening of flower beds which eventually fall from plants, Asthama, Bronchitis in human beings

 NOx §  NO3-   Acts as a fertilizer to the soil

§  Automobile exhaust produces NO2 which damages plant leaves & retard rate of photosynthesis

§  Automobile exhaust also causes red haze & lung irritation

HCs §  Formed by incomplete combustion of fuels esp. automobile

§  Carcinogenic – Causes cancer, Causes early aging, Plants leaves shredding

CO2 §  Formed by respiration, burning of fuels, decomposition of lime, volcanic eruption

§  A major greenhouse gas

CO §  Formed by incomplete combustion of C, Automobile exhaust, Cigarette smoke

§  Blocks delivery of oxygen to tissues (Combines with hemoglobin to form carboxy-hemoglobin, which is highly stable & reduces oxygen carrying capacity of blood)

§  Helps in production of steel & in extraction of Fe from Fe ore

Classical Smog  §  Occurs in cool humid climate

§  Chemically reducing hence called reducing smog

§  Smoke + fog + SO2

Green House Gases §  CO2, CH4, CFC, N2O, SF6, HFCs, PFCs, CCl4, CH3CCl3
CH4 §  It is mainly CH4 which burns in fossil fuels, produced by burning of vegetation or rotting

 

Photochemical Smog

  • Occurs in warm, dry & sunny climate
  • Results from the action of sunlight on unsaturated HC & oxides of Nitrogen produced by factories & automobile
  • Chemically oxidizing hence called oxidizing smog
  • Ozone + Acrolein + Formaldehyde + Peroxyacetyl Nitrate (PAN) are produced which cause serious health problems, severe plant damage, cracking of rubber & corrosion
  • Catalytic Converter – Prevent release of NO & HC to environment

 

Ozone Depletion

  • Ozone protects us from UV rays which causes skin cancer (Melanoma)
  • Depletion of ozone layer – By Ozone depleting substances (ODS) which are non-toxic, non-reactive & nonflammable
  • Main ODS– CFCs, HCFCs, Halons, CCl4, NOx, CH3CCl3 (Methyl chloroform)
  • Major Sources – Solvent Cleansing products >Refrigeration & Air conditioners > Foam Products
  • CFCs are the most widely used ODS, accounting for over 80% of total stratospheric ozone depletion
  • ODS + UV  Cl (Chlorine radicals which causes breakdown of Ozone)

 

Acid Rain

  • Acid rain (Ph < 5.6) is caused by emissions of sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids (H2SO4& HNO3) 
  • Rain with Ph < 5.6
  • Rain with oxides of sulfur & nitrogen (SO2 & NO2)

 

 

Fractional Distillation of Crude Oil

  • Crude oil is heated until it boils and then the hydrocarbon gases are entered into the bottom of the fractionating column.
  • As the gases go up the column the temperature decreases.
  • The hydrocarbon gases condense back into liquids and the fractions are removed from the sides of the column.
  • Higher HC degrade into lower HC by high heating (cracking) in following order –
  • Gaseous HCs
  • Petroleum Ether
  • Gasoline
  • Kerosene
  • Diesel / Gas Oil
  • Lubricating oil / Greases
  • Paraffin Wax
  • Asphalt & Coke

Biotechnology, Vitamins, Carbohydrates, Proteins, Lipids, Nucleic Acid

Branches of life sciences

Zoology Study that covers animals and animal life
Genetics Study about heredity
Pathology About diagnosing, treating, preventing illness,  disease, and injury
Embryology The study on how a baby grows in your tummy and other developments
Physiology The study of body parts

 

Biotechnology

  • Biotechnologyis the use of living systems and organisms to develop or make useful products
  • Can also be defined as “any technological application that uses biological systems, living organisms or derivatives thereof, to make or modify products or processes for specific use”

 

Bioinformatics
  • An interdisciplinary field which addresses biological problems using computational techniques, and makes the rapid organization as well as analysis of biological data possible
  • May also be referred to as computational biology, and can be defined as, “conceptualizing biology in terms of molecules and then applying informatics techniques to understand and organize the information associated with these molecules, on a large scale
Blue biotechnology Marine and aquatic applications of biotechnology
Green biotechnology Applied to agricultural processes
Red biotechnology Applied to medical processes
White biotechnology Also known as industrial biotechnology, is biotechnology applied to industrial processes

Nanotechnology

  • Nanotechnology(“nanotech”) is the manipulation of matter on an atomic, molecular, and supramolecular scale
  • Nanotechnology is the engineering of functional systems at the molecular scale
  • Application of nanotechnology includes majorly –
  • Inexpensive, efficient solar energy systems, a renewable, zero-carbon emission source
  • Desktop computers with a billion processors
  • Medical devices able to destroy viruses and cancer cells without damaging healthy cells
  • Materials 100 times stronger than steel
  • Superior military systems
  • More molecular manufacturing systems

 

Vitamin, Their Chemical Names & Deficiency Diseases

Vitamin Solubility Chemical Name Deficiency Disease
Vitamin A Fat Soluble Retinol Night Blindness, Hyperkeratosis, Keratinization
Vitamin B1 Water Soluble Thiamine Beriberi, Heart failure
Vitamin B2 Water Soluble Riboflavin Angular stomatitis, Mouth Disorders, Photophobia
Vitamin B3 Water Soluble Niacin Pellagra
Vitamin B7 Water Soluble Biotin Dermatitis, Enteritis (Inflammation of intestines)
Vitamin B12 Water Soluble Cyanocobalamin Pernicious anaemia
Vitamin C Water Soluble Ascorbic Acid Scurvy, Pyrexia
Vitamin D Fat Soluble Calciferol Rickets, Osteomalacia
Vitamin E Fat Soluble Tocoferol Sexual Reproduction Problems
Vitamin K Fat Soluble Phylloquinone Bleeding disease

 

  • Vitamin C     → Helps to heal wound & in immunity to the body; Artificially synthesized
  • Vitamin B12 → Contains Cobalt
  • Vitamin B2   → Gives yellow color to milk
  • Vitamin A     → Anti-infective vitamin
  • Vitamin K     → Helps in Blood clot

 

Macromolecule

Building Block

Carbohydrates Monosaccharides
Protein Amino acids
Lipids Glycerol + fatty acids
Nucleic acids Nucleotides

 

Carbohydrates

  • Carbohydrates are the polyhydroxy organic compounds made up of carbon, hydrogen and oxygen in which the ratio of hydrogen and oxygen hydrogen is 2:1 exactly as H2O (2:1)
  • Carbohydrates may be classified into the following four major groups viz.
Monosaccharides
  • Monosaccharides are the simplest form of carbohydrates.
  • All carbohydrates are reduced to this state before absorption and utilization.

 

Disaccharide
  • Disaccharides consist of two covalently joined monosaccharide
  • They produce two molecules of the same or different monosaccharides on hydrolysis
  • Examples include lactose, sucrose, maltose

 

Oligosaccaharides
  • Oligosaccaharides consist of few number (2-6) of monosaccharide units e.g., glycoproteins.

 

Polysaccharides
  • Polysaccharides are composed of many molecules of monosaccharides linked together e.g., Glycerole

 

Proteins

  • Are macromolecules or bio molecules composed of amino acids linked by peptide bondg. hemoglobin, albumin, globulin, enzymes etc.
  • The constituent elements of proteins are carbon (54%), hydrogen (7%), nitrogen (16%), oxygen (22%) and some may contain sulfur (1%) or phosphorus (0.6%)
  • Proteins acts as enzymes – accelerate the rate of metabolic reactions
  • Perform hereditary transmission by nucleoproteins of the cell nucleus.
  • Maintain colloidal osmotic pressure of blood
  • As hormones, growth factors – perform regulatory functions and gene activators.

 

Lipids

  • Group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (vitamins A, D, E, and k),  monoglycerides, diglycerides, triglycerides, Phospholipids and others
  • Main biological functions of lipids include storing energy, signaling, and acting as structural components of cell membranes
  • Lipids are hydrophobic and insoluble in water because they contain a hydrocarbon tail of CH2s that is nonpolar and repellant to water.

 

Nucleic acid

  • Nucleic acids, which include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are made from monomers known as nucleotides
  • Each nucleotide has three components: a 5-carbon sugar, a phosphate group, and a nitrogenous base
  • If the sugar is deoxyribose, the polymer is DNA. If the sugar is ribose, the polymer is RNA.
  • When a cell divides, its DNA is copied and passed from one cell generation to the next generation.
  • DNA is organized into chromosomesand found within the nucleus of our cells.
  • RNA is essential to the synthesis of proteins. It is also a component of cell organelles called
  • Information contained within the genetic code is typically passed from DNA to RNA to the resulting proteins.

Prominent Elements & Compounds

Carbon & Its Compounds

Catenation Self-linking property to form a long chain
Carbon Black Soot obtained when NG, Kerosene, Petroleum etc. are burnt in limited supply of air
Coke By destructive distillation of coal
Wood Charcoal Strong heating of coal in limited supply of air
Sugar Charcoal By Action of H2SO4 on cane sugar
Animal Charcoal By Heating bones in absence of air

Allotropy

  • A chemical element is said to exhibit allotropy when it occurs in two or more forms in the same physical state; the forms are called allotropes.
  • Allotropes generally differ in physical properties such as color and hardness; they may also differ in molecular structure or chemical activity, but are usually alike in most chemical properties.

 

Allotropes of Carbon

Diamond §  Each carbon atom in a diamond is covalently bonded to four other carbons in a tetrahedron

§  Used for cutting, drilling , grinding , and polishing

§  Hardest known natural mineral & a potential semiconductor material

Graphite §  Unlike diamond, graphite is an electrical conductor

§  Graphite powder is used as a dry lubricant

§  Most stable allotrope of carbon & slightly more reactive than diamond

Buckminster fullerene (C 60) §  A class of carbon allotropes in which carbon takes the form of a hollow sphere, ellipsoid, or tube

§  This class of materials includes carbon nanotubes, buckyballs, and the newly discovered nanobuds

Graphene §  A single layer of carbon atoms arranged in one plane

§  Layers of graphene make up graphite viz. a single layer of graphite is called graphene

§  Has high electron mobility and its possible applications in electronics

§  Basic structural element of carbon allotropes such as graphite, charcoal, carbon nanotubes, and fullerenes

Amorphous carbon §  Carbon that does not have any crystalline structure

§  Coal and soot or carbon black are informally called amorphous carbon

Carbon nanotubes §  Are cylindrical carbon molecules having extraordinary strength

§  Have unique electrical properties, and efficient conductors of heat

 

Prominent Elements & Compounds

Chlorine Disinfectant of water
Liquid Hydrogen Used as rocket fuel
Zinc Used in Galvanising iron to prevent it from rusting
AgCl & AgBr Used in black & white photography (Photo chromatic glass)
Cr & Ni Mfg of stainless steel & electroplating of iron (Ni prohibits magnet prop. of iron)
Lead Used in car batteries
Zirconium Used to make bullet proof alloy steel
Hydrogen Manufacturing of Vanaspati ghee
Neon Gas Used in advertising signs
Argon gas Filled in light bulbs to prevent tungsten filament from reacting
Cesium Used in photoelectric cells
Beryllium Used in making windows of X rays
Lithium Bromide Acts as a sedative
Lithium chloride To regulate humidity in air conditioning plant
Boron fibres Used to make bullet proof vests & aircraft material
Aluminium Powder Used in flashlights for indoor photography
Borosilicate Pyrex glass – Heat & Shock resistant
Ceramics Aluminosilicates (Clay + Sand + Feldspar)
Silver paint Aluminium powder + Linseed oil
HF Used  to etch glass & manufacturing of glass shell for TV tubes
Helium Used in filling Balloons
Oxygen + Helium Used in artificial respirations in deep sea diving
Radon Treatment of cancer, X rays Photography

 

Keratome Diamond knife, used by eye surgeons to remove cataract from eyes
Isomers Same chemical formula but different structure (n butane & iso-butane)
Ethene Used in ripening of fruits
LPG Mixture of n-butane & iso-butane with small amount of ethane & propane
Blue flame Complete burning of fuel (full oxygen supply)
Yellow flame Incomplete combustion of flame
CNG Mainly CH4
Biodiesel Used as diesel additive (Veg oil + animal fat)
Universe Hydrogen (91 %) > Helium (9 %)
Human Body Hydrogen (60.5 %) > Oxygen (25.5 %)
Earth Crust Oxygen (60 %) > Silicon (20 %) > Aluminium (6 %)

 

Nitrogen  §  Filled in light bulbs to prevent tungsten filament from reacting

§  Used as refrigerant to prevent food material

§  Used to make TNT & Nitroglycerine (used as explosives)

Sulfur  §  Used in vulcanization of rubber

§  Used as disinfectant & fungicide

§  Used as refrigerant

§  Used to make gun powder

Ozone §  Used as a disinfectant & germicide for purifying water

§  Used for purifying air in crowded cinema hall

§  Used in manufacturing of artificial silk

Zeolites §  Aluminosilicates – Used as catalysts in petrochemical industries for cracking hydrocarbons

§  Covert alcohol to Gasoline

Cement §  Mixture of silicates & aluminates of calcium + small amount of gypsum

§  CaO.SiO2, CaO.Al2O3

Glass §  Silica (SiO2) in quatz when heated at 1600 – 1700 * C produces amorphous liquid which on cooling provides Qautz or Silica glass

 

Rarest, Heaviest & Most

Rarest Astatine Most abundant element in the Universe Hydrogen
Lightest Hydrogen Most abundant element in the human body Hydrogen
Heaviest Natural Uranium Most abundant element in the Earth crust Oxygen
Heaviest Density wise Osmium Most abundant metallic element in the earth’s crust Aluminum
Most Malleable Gold First artificial element Technetium
Most Ductile Gold Heaviest gaseous element Radon
Most Conductive Silver lightest metal element Lithium
Most Electronegative Fluorine Least dense metal Lithium

Section 3 → Defence & Technology articles for Civil Services Preparation

Solar System & Planets

Solar System

  • Our solar system consists of Sun + 8 Planets + 1 Dwarf planet (Pluto) + No. of Natural Satellites
  • Pluto was demoted to dwarf planet at 26th general assembly of International Astronomical Union held at Czech republic in 2006
  • Only sun has its own light, which is also the nearest star to the earth
Size – Wise Jupiter > Saturn > Uranus > Neptune > Earth > Venus >Mars > Mercury
Inner / Terrestrial Planets Earth, Venus, Mars, Mercury
Jovian / Outer Planets Jupiter, Saturn, Neptune, Uranus
No. of Satellites Jupiter (63) > Saturn (60) > Uranus (27) > Neptune (13) > Mars (2) > Earth (1) > Venus (0) & Mercury (0)   (Moon at Jupiter were found by Galileo)
Time Period of revolution of Planets around the sun Neptune > Uranus > Saturn > Jupiter > Mars > Earth > Venus > Mercury (88 days)

 

  • Asteroids – A belt of minor planets revolving around the sun between Mars & Jupiter
  • All Planets revolve west to east around the sun except Uranus & Venus which moves east to west around the sun (Retrograde motion)
  • A ray of light from sun takes about 8 mins 17 secs to reach the earth. Light takes about 1 second to reach us from the moon.

 

Uranus Maximum inclination of 98* towards the sun  known as lopsided planet
Earth §  Inclination of 23.5

§  Blue planet due to presence of water (Approx. 71% area)

Mercury No inclination at all
Venus §  Hottest planet  due to total absence of atmosphere at Mercury

§  Earth’s twin because of their close proximity in size, mass & density

Mars §  Red planet due to presence of Feo (Iron oxide) dust

§  Named after roman god of war

§  Believed to have the possibility of some plant life

Jupiter Distinguished from other planets by a circular light & dark bands
Saturn Planet with three rings around it

Famous Space-crafts shot in space

Spacecraft Planet Agency
Messenger Mercury NASA
Curiosity Mars NASA
Viking Mars NASA
Pioneer Jupiter NASA
Cassini Saturn NASA / ESA / ASI (Italy)
New Horizon Pluto NASA
Aditya (2017-18) Solar Corona ISRO
Rosetta Asteroids & Comets ESA (Europe)
Phoenix Collection of soil samples near the northern pole to search for water at Mars NASA
Mars Orbiter Mission Mars ISRO

Sun

  • Sun is the only star in our Solar System as it has its own source of light and energy.
  • Mass of the Sun accounts to 99.86% of our Solar System.
  • Its average distance from the Earth is around 149,600,000 km.
  • Sunlight takes about 8 min 17 secs to reach the Earth.
  • Sun’s energy is produced by constant nuclear fusion in its core through a series of processes called the p-p (proton-proton) chain. This process converts Hydrogen into Helium.

 

Composition of sun 

  • Hydrogen    74.9%
  • Helium        23.8%
  • Metals         1.3%

 

Structure of Sun

The structure of the Sun can be divided into several different layers as follows:

Core

  • The core of the Sun has the highest temperature and pressure among all layers.
  • The temperature of the core is around 15 million degree Celsius – is in ionized state called plasma
  • The solar energy is produced in the core by controlled nuclear fusion process.
  • The high temperature in the core helps in removing the electrons from hydrogen atoms and in creating numerous electrons and protons for nuclear fusion.

 

Radiative Zone

  • The Sun’s radiative zone is the section of the solar interior between the innermost core and the outer convective zone.
  • In the radiative zone, energy generated by nuclear fusion in the core moves outward as electromagnetic radiation.

 

Convective zone

  • In this zone the density of plasma is low.
  • This zone transports hot and light density fluids from the core region of high energy & temperature to the outer region of low energy & temperature.

Photosphere

  • This is the first visible layer of the Sun.
  • The temperature here is around 6000 degree Kelvin (5370 degree Celsius).
  • The solar spots are formed on this layer. The temperature of a solar spot is around 4500 degrees.

Solar spots  Temporary dark spots formed when the magnetic field bursts through the surface. It can slow down the flow of energy from the inside of the Sun – that’s what makes the sun spots cooler & darker than the surrounding photosphere.

Chromosphere

  • Chromosphere literally mean as ‘sphere of colour’.
  • This layer is dominated by emission lines.

 

Corona

  • This is the outermost layer of the Sun.
  • High temperature in this region gives it an unusual spectral feature of a highly ionised ion.
  • Chromosphere & corona are visible only during formation of Diamond Ring during Solar eclipse.

 

Some Generic Space Terms

Asteroid A celestial body bigger than 10 m orbiting the Sun, mainly between Mars and JupiterMade of rock and metal, they can also contain organic compounds.Are similar to comets but do not have a visible coma (fuzzy outline and tail) like comets do
Meteoroid A meteoroid is a small rock or particle of debris in our solar system. They range in size from dust to around 10 metres in diameter (larger objects are usually referred to as asteroids).
Meteor A meteoroid that burns up as it passes through the Earth’s atmosphere is known as a meteor. If you’ve ever looked up at the sky at night and seen a streak of light or ‘shooting star’ what you are actually seeing is a meteor.
Fireball A very bright meteor (brighter than the planet Venus).
Bolide A fireball that explodes during its atmospheric flight, often with visible fragmentation.
Meteorite The part of a meteoroid or asteroid that survives the passage through our atmosphere and reaches the Earth’s surface.
Comet A smaller celestial body mainly composed of ice, rock and dust. As comets travel close to the Sun, some of the ice melts off and becomes a gas. This melting process causes bits of dust and debris to trail behind the comet. This tail can be seen in the night sky as a bright, quickly-moving light

 

Halley’s Comet

  • Halley’s Comet is arguably the most famous comet.
  • It is a “periodic” comet and returns to Earth’s vicinity about every 75 years, making it possible for a human to see it twice in his or her lifetime.
  • The last time it was here was in 1986, and it is projected to return in 2061.

The comet is named after English astronomer Edmond Halley, who examined reports of a comet approaching Earth in 1531, 1607 and 1682. He concluded that these three comets were actually the same comet returning over and over again, and predicted the comet would come again in 1758.

Types of Satellites

  • Satellite refers to a machine that is launched into space and moves around Earth or another body in space.
  • A satellite is an artificial object which has been intentionally placed into orbit.
  • Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as Earth’s Moon & Sun’s Earth

 

Why we need satellites?

  • Satellites have allows us to see large areas of Earth at one time.
  • This ability means satellites can collect more data, more quickly, than instruments on the ground.
  • Satellites also can see into space better than telescopes at Earth’s surface.
  • Reason being that satellites fly above the clouds, dust and molecules in the atmosphere that can block the view from ground level.

 

Parts of a Satellite

  • All satellites have at least two parts in common – an antenna and a power source.
  • The antenna sends and receives information, often to and from Earth
  • The power source can be a solar panel or battery
  • Many satellites carry cameras and scientific sensors.
  • Sometimes these instruments point toward Earth to gather information about its land, air and water
  • Other times they face toward space to collect data from the solar system and universe

 

How Do Satellites Orbit Earth?

  • A satellite orbits Earth when its speed is balanced by the pull of Earth’s gravity.
  • Without this balance, the satellite would fly in a straight line off into space or fall back to Earth.
  • Satellites orbit Earth at different heights, different speeds and along different paths. The two most common types of orbit are Geostationary and Polar
  • A geostationary satellite travels from west to east over the equator. It moves in the same direction and at the same rate Earth is spinning.
  • From Earth, a geostationary satellite looks like it is standing still since it is always above the same location.
  • Polar-orbiting satellites travel in a north-south direction from pole to pole. As Earth spins underneath, these satellites can scan the entire globe, one strip at a time

 

Types of Satellites

  • Satellites can be classified by their function since they are launched into space to do a specific job.
  • For ex. satellite that is launched to monitor cloud patterns for a weather station will be different than a satellite launched to send television signals.
  • Below mentioned are few of the most regular types of satellites launched into space

 

Communication Satellites

  • Communications satellites allow radio, television, and telephone transmissions to be sent live anywhere in the world.
  • The purpose of communications satellites is to relay the signal around the curve of the Earth allowing communication between widely separated points
  • Communication Satellites use Microwaves and Radio waves for  transmitting signals

Before communication satellites, transmissions were difficult or impossible at long distances. The signals, which travel in straight lines, could not bend around the round Earth to reach a destination far away. Now as communication satellites are in orbit, the signals can be sent instantaneously into space and then redirected to another satellite or directly to their destination.

  • There are two major classes of communications satellites, passive and active
  • Passive  bouncing signals from the Earth back to another location on the Earth
  • Active  carry electronic devices called transponders for receiving, amplifying, and re-broadcasting signals to the Earth

 

Communications satellites India

  • Indian National Satellite (INSAT) Series
  • GSAT Satellites Series

 

Navigation satellites

  • A system of satellites that provide autonomous geo-spatial positioning with global coverage
  • Designed expressly to aid the navigation of sea and air traffic via. Radio waves
  • It allows small electronic receivers to determine their location to high precision using time signals transmitted along a line of sight by radio from satellites
  • A satellite navigation system with global coverage may be termed a global navigation satellite system (GNSS)
  • Currently Global Positioning System (GPS) and the Russian GLONASS are only globaly operational GNSSs
  • China is in the process of expanding its regional BeiDou Navigation Satellite System into the global Compass navigation system by 2020.
  • European Union’s Galileo is a GNSS in initial deployment phase, scheduled to be fully operational by 2020
  • Japan is developing a regional based navigation system viz. Quasi-Zenith Satellite System

 

India has a regional satellite-based augmentation system, GPS Aided GEO Augmented Navigation (GAGAN), which enhances the accuracy of NAVSTAR GPS and GLONASS positions, and is developing the Indian Regional Navigation Satellite System (IRNSS)

 

Remote Sensing Satellites

  • Remote sensing is observing and measuring our environment from a distance viz. earth observation satellites
  • The electromagnetic radiation is normally used as an information carrier in remote sensing.
  • The output of a remote sensing system is usually an image representing the scene being observed.

The data from these satellites are used for several applications covering agriculture, water resources, urban planning, rural development, mineral prospecting, environment, forestry, ocean resources and disaster management.

 

Remote Sensing Satellites India

  • Indian Remote sensing (IRS) satellite series
  • Cartosat; Oceansat; & RISAT (Resource Sat) Satellites
  • Bhaskara Satellites; Megha-Tropiques Satellites
  • Satellite with ARgos and ALtiKa (SARAL)

 

Space Exploration Satellites

  • Space exploration satellites are not really satellites at all; they are properly known as space probes.
  • Space probes send back detailed pictures and atmospheric data of planets and other stellar phenomena
  • Space exploration satellites must be built to last because it takes so long for the satellites to reach their destinations.
  • Jupiter’s rings were discovered by a space exploration satellite

 

Space Exploration Satellites India

  • Stretched Rohini Satellite Series (SROSS)
  • Chandrayaan 1
  • Mars Orbiter Mission – Mangalyaan
  • The satellite is moving the fastest at the low point of an elliptical orbit viz. perigee
  • The high point of the orbit, when the satellite is moving the slowest, is apogee

Launch Vehicles for Satellites & Space Probes

§  Launch Vehicles are used to transport and put satellites & space probes into space

§  Satellites Orbits Height Classification to under different types of launch vehicles

Lower earth orbit 180 km – 2000 km Sun synchronous orbit, Polar Orbit
Mid earth orbit 2000 km – 35780 km GPS & Navigation
High earth orbit > 35780 km Geostationary orbit

§  The first Indian experimental Satellite Launch Vehicle (SLV-3) was developed in 1980

§  An Augmented version of this, ASLV, was launched successfully in 1992

 

 

India has made tremendous progress in launch vehicle technology & has achieved self-reliance in satellite launch vehicle programme with the operationalisation of Polar Satellite Launch Vehicle (PSLV) and Geosynchronous Satellite Launch Vehicle (GSLV)

Satellite Launch Vehicle (SLV)

§  The Satellite Launch Vehicle (SLV) project was born out of the need for achieving indigenous satellite launch capability

§  SLV3, India’s first experimental launch vehicle, was capable of placing 40 kg class payloads in Low Earth Orbit (LEO)

§  It was a four-stage rocket with all solid-propellant motors – weighing 17 tonnes with a height of 22 m

§  The launch on July 18, 1980 from Sriharikota Range, successfully placed Rohini satellite, into the orbit, thereby making India the sixth member of an exclusive club of space-faring

 

The successful culmination of the SLV-3 project showed the way to advanced launch vehicle projects such as the Augmented Satellite Launch Vehicle (ASLV), Polar Satellite Launch Vehicle (PSLV) and the Geosynchronous satellite Launch Vehicle (GSLV)

Augmented Satellite Launch Vehicle (ASLV)

§  The Augmented Satellite Launch Vehicle (ASLV) Programme was designed to augment the payload capacity to 150 kg, thrice that of SLV-3, for Low Earth Orbits (LEO).

§  With a lift off weight of 40 tonnes, the 23.8 m tall ASLV was configured as a five stage, all-solid propellant vehicle to Low Earth Orbit (LEO)

 

Polar Satellite Launch Vehicle (PSLV)

§  PSLV is capable of launching 1750 kg satellites in sun-synchronous polar orbit and 1425 kg satellite in geo-synchronous transfer orbit.

§  It measures 44.4 m tall, with a lift off weight of 320 tonnes & known as the Workhorse of ISRO

§  PSLV has four stages using solid and liquid propulsion systems alternately

§  PSLV has proved its multi-payload, multi-mission capability in a single launch and its geosynchronous launch capability

§  Launched Missions  Chandrayaan-1, Mars Orbiter Mission, Space Capsule Recovery Experiment, IRNSS, Astrosat

 

Geosynchronous Satellite Launch Vehicle (GSLV)

§  The Geosynchronous Satellite Launch Vehicle (GSLV) was primarily developed to launch INSAT class of satellites into Geosynchronous Transfer Orbits.

§  Presently GSLV is being used for launching GSAT series of satellites.

§  GSLV is capable of placing 2 ton class of satellites viz. INSAT and GSAT into Geosynchronous Transfer Orbit (GTO)

§  Payload to LEO is 5,000 kg & Payload to GTO is 2500 kg

§  GSLV is a 49 m tall, three stage vehicle with a lift-off mass of 415 ton.

§  The first stage is solid propellant motor stage

§  The second stage is liquid propellant stage

§  Third one is cryogenic stage viz. uses liquid hydrogen as fuel & liquid oxygen as oxidizer

§  Cryogenic rocket engine – Fuel or oxidizer (or both) is gases liquefied and stored at very low temperatures

 

Difference Between PSLV & GSLV

PSLV (Polar satellite launch vehicle) 

§  First launch 1993

§  Can carry upto 1425 kg satellite in GTO

§  Can carry upto 1750 kg in LEO orbit

§  For launching Indian remote sensing satellites (IRS)

§  Used for Chandrayaan & Mars Mission

§  four stages propellant using solid and liquid propulsion systems alternately

GSLV (Geosynchronous satellite launch vehicle) 

§  First launch 2001

§  Can carry upto 2500 kg satellite in GTO orbit

§  Can carry upto 5000 kg satellite in LEO orbit

§  Developed mainlyfor launching Indian National satellites (INSAT)

§  Next version is GSLV MK-3

§  Three stages propellant using solid, liquid & cryogenic propulsion in order

Geosynchronous Satellite Launch Vehicle MK3 (GSLV Mk 3) / LVM3

§  LVM 3 is a heavy launch capability launcher being developed by ISRO

§  Have Multi-mission launch capabilities, can be used to launch satellites into different orbits

§  It will allow India to achieve complete self-reliance in launching satellites as –

§  It will be capable of placing 4 tonne class Geosynchronous satellites into GTO

§  It will be capable of placing 8 tonne class satellites into LEO

§  LVM3 wll have same 3 stages as GSLV but it will have an India built cryogenic stage with higher capacity than GSLV

 

Difference Between GSLV & GSLV Mk3

GSLV 

§  Can carry upto 2500 kg in GTO orbit

§  49 meters tall

§  Lift off weight – 414 tonnes 

GSLV – Mark 3 

§  Can carry upto 4500-5000 kg satellites in GTO orbit

§  Until now, we relied on EU’s Arianespace launch vehicle for heavy satellites viz. INSAT 4 class

§  42.4 meters – Shorter than ordinary GSLV

§  Lift off weight – 629 tonnes

LVM3-X/CARE Test Flight

§  First experimental flight of LVM3, lifted off from Sriharikota on December 18, 2014

§  Directed By – Human Crew module Atmospheric Reentry Experiment (CARE)

§  To check its atmospheric stability with luggage of around 4 tonne

§  To study re-entry characteristics of the crew module

§  Did not use cryogenic engine in test stage & carried only a passive (non-functional) cryogenic engine in upper stage

 

GSLV MK III with cryogenic upper stage successfully tested

§  The GSLV D-6 is the second successful consecutive launch (earlier launch GSLV D-5 in January) of the GSLV series with indigenous cryogenic upper stage.

§  ISRO is planning to test GSLV Mk III capable of carrying payload up to four tonne by the end of next year.

 

Significance of GSLV MK3

§  GSLV will cost just one third of money spent on foreign agencies, which will reduce satellite launch cost as well as will save Forex

§  It will enhance India’s capability to be a competitive player in the multimillion dollar commercial launch market. It will help in earning foreign exchange.

§  The GSLV will help ISRO put heavier communication satellites of GSAT class into orbit.

§  Reduction of dependence on foreign agencies gives strategic boost in this high tech sector

 

Types of Launch Engines

Solid Fuel Engine

§  Once fired continue to be in operation till their fuel burns off

§  Can’t control its velocity or direction

 

Liquid Fuel Engine

§  Can be shut off once the spacecraft achieves the desired velocity

§  Can restart the engine several times if required, making it possible to change satellite’s orbit with precision

 

LAM – Liquid Apogee Motor

§  A special device on liquid-fuel powered engines, which helps to move the satellite in a precise orbit

§  Recently, ISRO used LAM on its Mars orbiter and on IRNSS satellites

 

ISRO indigenous cryogenic engine CE-20 with four-tonne capacity

§  Enable scientists to put satellites of up to the capacity of four tones in geostationary orbit

§  So far India’s GSLVs were being powered by cryogenic engines given by Russia

 

Cryogenic engine 

§  Generally uses Hydrogen as fuel and liquid oxygen as oxidizer stored at very low temperature

§  evelop the thrust needed in the final state of the rocket to put satellites into a geosynchronous orbit

 

The cryogenic stage is technically a very complex system, as compared to solid liquid propellant stages, due to its use of propellants at extremely low temperature (cryo) and the associated thermal and structural challenges. A cryogenic rocket stage is more efficient and provides more thrust for every kilogram of propellant it burns.

ISRO’s Reusable Launch vehicle

§  This launch vehicle (1.5 tonne) will be mounted on the Polar Satellite Launch Vehicle (PSLV) rocket

§  At an altitude of 70 km, the model would get separated and would glide back to earth

§  The descent speed would be controlled through the fins on the machine

§  It will bring down costs significantly of launching satellites by one-tenth

Sakaar

§  ISRO’s Augmented Reality application designed for Android devices

§  It consists of 3D models of rockets (PSLV, GSLV Mk-III); videos of INSAT 3D-predicting cyclones Mars Orbiter Mission (MOM) orbit insertion, launch video of MOM, Anaglyph of Mars surface.

§  Augmented Reality is a live direct view of a physical, real-world environment whose elements are augmented by computer-generated 3D models, animations, videos etc.

§  It enhances user’s current perception of reality

§  AR requires three elements – Android device with back camera, AR application and AR markers

Mars Orbiter Mission India (Mangalyaan)

Few Facts About Planet Mars

§  Mars has two moons viz. Phobos and Deimos

§  One Martian year is of 687 days

§  Mars gravity is 1/3rd  of Earth

§  One Martian day equals 24 hours 37 minutes

 

Mangalyaan

§  Launch vehicle PSLV (Polar satellite launch vehicle) from Sriharikota, Andhra Pradesh

§  First Indian spacecraft to cross Earth’s escape velocity of 11.2 km per second

 

Why Mangalyaan was sent to Mars?

Purpose Device To Study
Surface Study Color Camera §  Surface, dust storms etc.

§  Take photos of Mar’s satellites Phobos and Deimos

Atmosphere MENCA §  Mars Exospheric Neutral Composition Analyzer

§  To study neutral gas atoms in the Martian atmosphere

Methane Sensor §  Methane Sensor for Mars (MSM)

§  If methane + water detected It’s possible that at some point of time, Mars had supported life form

Photometer §  Lyman Alpha Photometer (LAP) To Measure hydrogen and deuterium

§  Knowing Hydrogen : Deuterium ratio will help answer how did water vanish from Mars

Minerals Spectrometer §  Thermal Infrared Imaging spectrometer (TIS)

§  To study mineral resources of Mars

ISTRAC (ISRO Telemetry, Tracking & Command Network) – Bangalore

§  Previously tracked and commanded Chandrayaan -1

§  Also did tracking for Mars orbiter Mangalyaan mission

 

Lunar Missions India – Chandrayaan

Chandrayaan 1

§  Launch vehicle PSLV (Polar satellite launch vehicle) from Sriharikota, Andhra Pradesh

§  India’s maiden moon exploration mission ‘Chandrayaan-1’ was launched in October 2008

§  for mapping the lunar surface with high resolution remote sensing

§  to study the chemical and mineralogical composition

§  This mission has enabled to detect the presence of Hydroxyl (OH), a molecule consisting of oxygen and hydrogen atoms and water molecules on the lunar surface, which has set new directions of lunar explorations in the global community.

 

Chandrayaan 2

§  Russian Federal Space Agency (Roscosmos) and ISRO signed an agreement to work together on the Chandrayaan 2 project

§  ISRO would have the prime responsibility for the orbiter and rover, while Roscosmos was to provide the lander.

§  Chandrayaan 2 is India’s second lunar exploration mission after Chandrayaan 1.

§  Developed by ISRO, the mission is planned to be launched to the Moon by a GSLV Mk III

§  India is planning to launch Chandrayaan-2 by 2018

§  The wheeled rover will move on the lunar surface and will pick up soil or rock samples for on-site chemical analysis.

§  The data will be relayed to Earth through the Chandrayaan 2 orbiter.

 

Few Famous Space Exploration Missions

Spacecraft Planet Agency
Apollo Moon NASA
Messenger Mercury NASA
Curiosity – Robotic Rover Mars NASA
Viking Mars NASA
Pioneer Jupiter NASA
Cassini Saturn NASA / ESA / ASI (Italy)
New Horizon Pluto NASA
Aditya (2017-18) Solar Corona ISRO
Rosetta Asteroids & Comets ESA (Europe)
Phoenix Collection of soil samples near the northern pole to search for water at Mars NASA
Mars Orbiter Mission Mars ISRO

 

Comet Mission – Philae

§  Europeans Rosetta spacecraft’s mission to study comets, landed a spacecraft on comet for the 1st time in history

§  Rosetta – took off from Earth 10 years ago carrying Philae & became the first spacecraft to orbit a comet

§  Philae – a robotic European Space Agency lander attached to Rosetta; transmit data from the surface about the comet’s composition

 

Philae

§  a robotic European Space Agency lander that accompanied the Rosetta spacecraft until it landed on comet 67P

§  Rosetta →Mothership (spacecraft) orbiting Comet 67P  Philae communicates with Rosetta which sends the received data to the earth

 

Objectives 

§  To focus on elemental, isotopic, molecular and mineralogical composition of the comet material

§  The large-scale structure and the magnetic and plasma environment of the nucleus

§  The mission seeks to unlock the long-held secrets of comets — primordial clusters of ice and dust that scientists believe may reveal how the Solar System was formed.

IRNSS, GAGAN, GSAT, ASTROSAT

Indian Regional Navigation Satellite System (IRNSS)

§  With an investment of 1420 Cr, 7 Satellites to be put in space by ISRO

§  Will cover India + 1,500 km beyond its borders

§  3 satellites will be put in geostationary orbit + 4 satellites in pairs in two inclined geosynchronous orbits

§  From the ground, these satellites will appear to travel in figures of ‘8’ during the course of a day

§  Will be at a height of about 36,000 km, launched from Satish Dawan Space Centre in Sriharikota

§  Will need a special receiver equipment to use navigation data, standard GPS receiver will not work

At present only two countries have fully functional global navigation systems

USA GPS – Global
Russia GLONASS – Global
China Beidou – Regional  Will be global by 2020
Japan Quasi-Zenith Satellite System
European Union Galileo (GNSS)

 

IRNSS Scientific principle

Microwaves

§  Use two microwave frequency bands: L5 and S which travel at speed of light.

§  Receiver will calculate the delay between microwave’s transmission & its reception, thus we get coordinates on earth.

 

Atomic Clocks

§  For above microwave-calculation, Satellites have to periodically transmit their precise position in orbit with exact time, hence, they need to carry extremely accurate clocks with long shelf-life.

§  Therefore, Each IRNSS satellite is equipped with rubidium atomic clocks, to keep precise time.

 

Services

§  Will provide two kinds of services viz. Standard Positioning Services, available to all users, and an encrypted service, provided only to authorized users

§  IRNSS System is expected to provide a position accuracy of better than 20 m in the primary service area

§  To be able to use the IRNSS satellites, ISRO have to launch at least four of the seven planned IRNSS satellites

 

Global Positioning System Aided Geo Augmented Navigation System (GAGAN)

§  A joint effort by the ISRO & Airports Authority Of India (AAI) for civil aviation purposes

§  Aimed to help Air traffic control and helps pilots fly / land aircrafts in bad weather

§  Depends on GPS (American navigation system)

 

India has become 4th nation after US, Europe & Japan to have inter-operable Satellite Based Augmentation System (SBAS) & 1st in the world to serve the equatorial region

Working Pattern – GAGAN

§  Works with the help of 3 Geostationary Satellites viz. GSAT-8, GSAT-10 and GSAT-15

§  works by augmenting and relaying data from GPS satellites with the help of augmentation satellites and earth-based reference stations

§  GAGAN system corrects any anomalies in the position data and gives accurate routes, landing guidance and time saving information to the pilots

§  system would be available for the member states of the South Asian Association for Regional Cooperation (SAARC)

§  It will be able to help pilots to navigate in the Indian airspace by an accuracy of 3 m

 

Major Benefits of GAGAN

§  Improved efficiency,

§  Direct routes

§  Increased fuel savings

§  Significant cost savings

 

Major drawback   only those aircraft that are fitted with satellite-based wide area augmentation system (SBAS) will be able to use the new technology

GSAT 16

§  INSAT-3E is a communication satellite that powers DD & private TV channels, internet & radio signals.

§  INSAT-3E is getting old and outdated, even stopped working in March 2014, after serving for almost a decade, hence need to be replaced with GSAT-16

§  GSAT 16 is configured to carry a total of 48 communication transponders, the largest number of transponders carried by a communication satellite developed by ISRO so far

§  The designed on-orbit operational life of GSAT-16 is 12 years.

§  Placed in Geosynchronous Transfer Orbit at 55 degrees East longitude by European Ariane-5 launcher

 

GSAT 6 

§  It is aimed at primarily benefiting the country’s strategic and social applications

§  Has life period of nine years & will povide S-band communication services in the country

§  It includes a first-of-its-kind S-Band antenna with a diameter of six meter. This is the largest antenna ISRO has ever made for a satellite.

§  It will offer a Satellite Digital Multimedia Broadcasting (S-band) service, via mobile phones and mobile video/audio receivers for vehicles.

 

ASTROSAT

§  India’s 1st dedicated astronomy multi-wavelength satellite, aimed at studying distant celestial objects

§  ASTROSAT will observe universe in the optical, Ultraviolet, low and high energy X-ray regions of the electromagnetic spectrum

§  1st mission to be operated as a space observatory by ISRO

Scientific objectives of ASTROSAT

§  To understand high energy processes in binary star systems containing neutron stars and black holes

§  Estimate magnetic fields of neutron stars

§  Study star birth regions and high energy processes in star systems lying beyond our galaxy

§  Detect new briefly bright X-ray sources in the sky

§  Perform a limited deep field survey of the Universe in the Ultraviolet region

INO, PROVe, TOPs, NISAR

Polar Remotely Operated Vehicle (PROVe)

§  India’s first Polar Remotely Operated Vehicle (PROVe) operationalized in North Antarctica

§  Indigenously built by National Institute of Ocean Technology (NIOT) under Union Ministry of Earth Sciences

§  Will measure parameters like ocean currents, temperature, dissolved oxygen and salinity in the Antarctic

§  Monsoon prediction and reading of pattern will become easier

§  Capable of probing the sea bed under normal temperature and exploring up to 200 meters in inhospitable and tough regions

§  Successfully deployed in Priyadarshini Lake (Antarctica) by ESSO -NIOT

§  ESSO-NIOT – An Indo-US initiative under the Monsoon Mission program of the Union Ministry of Earth Sciences

§  Studying science behind the monsoonal events of Bay of Bengal using both Indian & US research ships

 

Significance of PROVe

§  The results and outcomes will help researchers in understanding the biological activities taking place inside the sea

§  Will help in forecasting Monsoon as it will measure parameters like ocean currents, temperature and salinity in the Arctic

§  It will especially help scientist to move away from present Mathematical models for forecasting the Monsoon which many times vary from initial forecasts

 

India based Neutrino Observatory (INO)

The India-based Neutrino Observatory (INO) Project is a multi-institutional effort aimed at building a world-class underground laboratory with a rock cover of approx. 1200 m for non-accelerator based high energy and nuclear physics research in India

§  Jointly effort by Department of Atomic Energy (DAE) & Department of Science & Technology (DST)

§  Place  Bodi west hills, Theni district, South Tamilnadu

 

Key Features of INO

§  Mega science project under 12th Five year plan, to setup an underground lab for pure science.

§  Has 50,000 tones magnetic detector + an Iron Calorimeter detector to study neutrinos & particle physics

 

What are Neutrinos?

§  Neutrinos are fundamental particles belonging to the lepton family.

§  They come in three flavours, one associated with electrons and the others with their heavier cousins the muon and the Tau.

§  According to standard model of particle physics, they are mass less.

§  However recent experiments indicate that these charge-neutral fundamental particles have finite but small mass which is unknown.

§  This was shown by observations of neutrino oscillation, which is a phenomenon by which one type of neutrino transforms into another.

Location factors of INO

§  To detect Neutrinos and their reactions, the lab has to be at least 1000 m below surface, to reduce natural cosmic radiation

§  Mountains of South India, are most ideal for this lab, because they’ve dense rock (mostly gneiss)

§  Bodi west hills is made up of Charnockite (hardest rock known) hence Earthquake risk minimum

§  One might wonder at the need for such a massive detector and for drilling underground.

§  The reason is that the neutrinos interact very weakly with the surroundings.

§  We are all being washed by a stream of neutrinos every passing minute as they just pass through us without leaving a trace.

§  Since they interact so weakly, detecting them over other interactions is impossible.

§  We need to have a barrier of at least 1 km of earth to keep itself away from all the trillions of neutrinos produced in the atmosphere and which would otherwise choke an over-the-ground neutrino detector. This is the reason scientists are now going underground.

 

Why Researching Neutrinos?

§  Neutrinos are very important for our scientific progress and technological growth as they are abundant & have very feeble mass and no charge, which means they can travel through planets, stars, rocks and human bodies without any interaction.

§  In fact, a beam of trillions of neutrinos can travel thousands of kilometres through a rock before an interaction with a single atom of the rock.

§  They hide within them a vast pool of knowledge and could open up new vistas in the fields of astronomy and astrophysics, communication and even in medical imaging, through the detector spin-offs.

 

Terrestrial Observation and Predicting System (TOPS)

Ramakrishna Nemani, an Indian scientist in NASA has modified and adapted NASA technology to help Indian farmers against floods, droughts, climate change and smooth implementation of crop-insurance.

§  TOPS system collects weather & climate data using remote sensing satellites, weather stations, climatic forecasting and ecosystem models

§  This data helps in categorizing agro-regions according to climate risk, thus, crop production and loss can be determine in advance.

§  Both farmer and Insurance companies can make ‘business’ decisions accordingly

§  Ensures that right amount of crop insurance reaches the right farmer.

 

NASA-ISRO Synthetic Aperture Radar Mission – NISAR

§  Aimed to measure the changes on earth’s land surface, ice surface, glaciers, earthquakes and volcanoes & to find causes and consequences of such changes

§  Will be launched by 2020 – NISAR will be the first satellite mission to use two different radar frequencies (L-band and S-band)

§  Hence It will capture resolution even less than a centimeter of earth’s surface

§  Preciseness required mainly to understand climate change & to predict natural disasters in advance

NASA to Provide 

§  L-band

§  GPS

§  Synthetic aperture radar (SAR)

§  Solid state recorder

§  Subsystems: Payload, Communication

ISRO to Provide 

§  S-band

§  Launch Vehicle

§  Spacecraft Bus

Missiles India

Ballistic Missiles

§  Launched from land or sea; follows a trajectory with the objective of delivering one or more warheads to a predetermined target

§  Usually carry a nuclear warhead and are very heavy & have much larger range

§  Only guided during relatively brief periods of flight, and most of its trajectory is unpowered and governed by gravity (and air resistance if in the atmosphere

§  Long range intercontinental ballistic missiles are launched at a steep,sub-orbital flight trajectory and spend most of their flight out of the atmosphere

§  Shorter range ballistic missiles stay within theEarth’s atmosphere

§  Examples include Agni Missiles, Prithvi Missiles, Akash, Trishul, Maitri, Dhanush, Sagarika, K4, K5

 

Cruise missiles

§  Can also be launched from air along with land and sea

§  Have their own engines and wings to strike the target

§  Can be sub-sonic (.8 mach), supersonic (3 mach) or hypersonic (5 mach)

§  Highly accurate & fly within Earth’s atmosphere

§  usually carry conventional warheads although some cruise missiles can also be equipped with nuclear warheads

§  Examples include Brahmos Missiles, Nirbhay Missile

 

In both cases viz. Ballistic Missiles & Cruise Missiles are guided. That is, the flight path is pre-determined and very small alterations in flight are possible, if at all.

Ballistic Missiles India

Agni Missiles

§  Ballistic missiles carrying nuclear warheads

§  Classified into three types viz. Medium Range Ballistic Missiles (MRBM), Intermediate Range Ballistic Missiles (IRBM) and Intercontinental Ballistic Missiles (ICBM)

Name Type Range (Km) Status Type
Agni I MRBM 700-1200 Deployed Surface to surface
Agni II IRBM 2000-2500 Deployed Surface to surface
Agni III IRBM 3000-5000 Deployed Surface to surface
Agni IV IRBM 2500-3700 Deployed Surface to surface
Agni V ICBM 5000-8000 Tested Surface to surface
Agni VI ICBM 10000-12000 Under Development Surface to surface

§  Agni-I,Agni-II and Agni-III missiles were developed under the Integrated Guided Missile Development Program

§  Agni IV + Agni V – high accuracy Ring Laser Gyro based Inertial Navigation System (RINS) and the most modern and accurate Micro Navigation System (MINS)

 

Prithvi Missiles

§  Surface-to-surface short-range ballistic missiles (SRBM)

Name Range (Km)
Prithvi I 150
Prithvi II 150-350
Prithvi III 350-650

§  Dhanush is the naval variant of Prithvi Missiles – Sea to Surface

§  Prithvi-II – 1st missile developed by DRDO under IGMDP

 

Prahaar

§  A solid-fuelled Surface-to-surface Missile with range of 150 km

§  Equipped with omnidirectional warheads and could be used for striking both tactical and strategic targets

 

India Sea Based Nuclear Armed Ballistic Missiles : Surface to Surface

§  Submarine-launched ballistic missiles (SLBM)

Name Range (Km)
Dhanush 350
Sagarika (K15) 700
K4 3500
K5 6000

Surface to Air Missiles of India

Name Feature Range
Akash surface-to-air 30 km
Trishul surface-to-air 12 km
Maitri surface-to-air 15 km

Akash Air Defence missile system 

§  Medium range Surface to air missile viz. approx. 35 km

§  Can employ multiple air targets while operating in fully autonomous mode

§  Can be launched from static or mobile platforms

§  Can carry conventional and nuclear warheads

§  Can operate in all weather conditions.

§  Developed under the integrated guided-missile development programme by ISRO

 

LRSAM – India-Israel joint venture missile

§  Long Range Surface to Air Missile (LRSAM) – called Barak 8 missile in Israel

§  can take down an incoming missile as close as 500 meters away from the ship

 

Integrated Guided Missile Development Program (IGMDP)

§  Prithvi Missiles – Short range surface-to-surface missile + Naval variant (Dhanush)

§  Trishul Missiles – Short range low-level surface-to-air missile

§  Akash Missiles  Medium range surface-to-air missile

§  Nag Missiles  Third-generation anti-tank missile

§  Agni Missiles – Only Agni 1, 2 & 3

 

Anti Tank Missile India

Nag Missile

§  “Fire-and-forget” anti-tank missile

§  An all-weather missile with a range of 3 to 7 km

§  Uses Imaging Infra-Red (IIR) guidance with day and night capability

§  Can be mounted on an infantry vehicle

A variant of NAG Missile to be launched from Helicopter is being developed under the Project named HELINA (HELIcopter launched NAg)

Cruise Missiles India

Brahmos Missiles

§  can be launched from submarines, ships, aircraft or land (Cruise Missiles)

§  Presently world’s fastest cruise missile in operation (Brahmos)

 

§  Brahmos – Mach 2.8 Supersonic Cruise Missile developed in collaboration with Russia – 300 km

§  Brahmos 11– Mach 7 Hypersonic Cruise Missile in development collaboration with Russia

 

Nirbhay

§  1st long range subsonic cruise missile

§  Can be launched from land, sea and air(Cruise missile)

§  a ring laser gyroscope for high-accuracy navigation and a radio altimeter for the height determination

§  Strike range – 1000 km

§  From Integrated Test Range at Wheeler island, Chandipur, Orissa, by SFC monitored by DRDO

Air to Air Missile India

Astra Missile – India’s 1st Air to Air (BVR)

§  Beyond Visual Range Air-to-Air Missile; smallest DRDO developed missile (3.8m)

§  capable of engaging targets at varying range and altitudes allowing for engagement of both short-range targets (up to 20 km) and long-range targets (up to 80 km) using alternative propulsion modes

 

Unmanned Aerial Vehicle

Panchi

§  Wheeled version of Unmanned Aerial Vehicle (UAV) Nishant capable of taking-off and landing using small airstrips

§  Have all the surveillance capabilities of UAV Nishant + longer endurance as it does not have to carry the air bags and parachute system as in the case of UAV Nishant

Nishant UAV

§  a multi-mission UAV with Day/Night operational capability, inducted in Army

§  designed for battlefield surveillance, target tracking & localization, and artillery fire correction

§  controlled from a user friendly Ground Control Station + image processing system to analyze transmitted images from UAV

India’s Cold start Doctrine

§  Though officially denied, it’s an offensive doctrine by the Indian strategic establishment

§  Aimed at reducing mobilization time and improved network-centric warfare capabilities

 

Goal

§  To establish the capacity to launch a retaliatory conventional strike against Pakistan that would inflict significant harm on the Pakistan Army before the international community could intercede

§  At the same time, pursue narrow enough aims to deny Islamabad a justification to escalate the clash to the nuclear level

 

Offensive operations could begin within 48 hours after orders have been issued. Such a limited response time would enable Indian forces to surprise their Pakistani counterparts.

Iasmania – Civil Services Preparation Online ! UPSC & IAS Study Material | Indian Navy Warships Projects Iasmania – Civil Services Preparation Online ! UPSC & IAS Study

 

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Indian Navy Warships Projects

INS Chakra

§  Nuclear powered submarine under a 10-year lease from Russia since 2012.

§  Negotiations are underway to lease an additional Akula-class attack submarine

 

Arihant Class Submarine

§  A class of nuclear-powered ballistic missile submarines being built for the Indian Navy

§  The lead vessel of the class, INS Arihant was launched in 2009

§  Arihant is the first ballistic missile submarine to have been built by a country other than one of the five permanent members of the UNSC

§  The 6,000 tonne vessel was built under the Advanced Technology Vessel (ATV) project at the Ship Building Centre in the port city of Visakhapatnam

§  INS Arihant is to be the first of the expected five in the class of submarines designed and constructed as a part of the Indian Navy’s secretive Advanced Technology Vessel (ATV) project

 

Project 17 – Shivalik class Frigate

§  The Shivalik class or Project 17 class is a class of multi-role frigates in service with the Indian Navy.

§  They are the first stealth warships built in India – built by Mazagon Dock Limited

§  A total of three ships were built between 2000 and 2010, and all three were in commission by 2012

 

Project 15 – Delhi Class destroyers

§  Delhi-class destroyers are guided-missile destroyers of the Indian Navy

§  Three ships of this class are in active service – INS Delhi, INS Mysore, INS Mumbai

§  The Delhi-class vessels are the third-largest warships to be fully designed and built in India, after the Kolkata-class destroyers and the Shivalik-class frigates

 

Project 15A – Kolkata Class Destroyer

§  The Kolkata class (Project 15A) are a class of stealth guided missile destroyers

§  The class comprises three ships – Kolkata, Kochi and Chennai – built by Mazagon Dock Limited

§  The destroyers are a follow-on of the Project 15 Delhi-class destroyers, but are considerably more capable than them

 

Project 15B – Visakhapatnam Class Destroyer

§  The Visakhapatnam class (Project 15B) is a class of stealth guided missile destroyers currently being built for the Indian Navy.

§  Based on the Kolkata-class design, the Visakhapatnam class will be an extensively improved version.

§  1st ship of Project 15B, a Guided Missile Destroyer Visakhapatnam largest missile destroyer commissioned in India till now

§  Will carry 8 BrahMos missiles

§  Future Ships under this project – Porbandar, Mormugao, Paradip

 

Project 17A

§  The Project 17A-class frigate is follow-on of the Project 17 Shivalik-class frigate for the Indian Navy.

§  A future project aimed at building country’s most advanced warships

§  Seven frigates will be built indigenously with stealth features to avoid easy detection by Mazagon Dock and GRSE

Project 75I

§  6 Diesel submarines with Air Independent Propulsion System (AIP) technology for Indian Navy by 2022

§  Conventional diesel-electric submarines have to surface every few days to get oxygen to recharge their batteries.

§  With AIP systems, they can stay submerged for much longer periods.

§  Will have both anti-surface and anti-submarine warfare viz. vertical launched BrahMos for the sea & land targets + Tube-launched torpedoes for anti-submarine warfare

§  AIP significantly improves stealth, as it enables a submarine to generate electricity for services and battery charging and propulsion while completely submerged.

 

Scorpene submarine to carry AIP

§  A class of diesel-electric submarine jointly developed by the French DCN and the Spanish company Navantia & now by DCNS under Project 75.

§  It features diesel-electric propulsion and an additional air-independent propulsion (AIP) system.

§  A DRDO-developed critical propulsion system will go into the last two of the six Scorpene submarines, being built under technology transfer at Mazagon Dock, Mumbai.

 

Aircraft Carriers –  INS Vikrant

§  Maiden indigenous aircraft carrier in India

§  Largest aircraft carrier after induction

§  Previous aircraft carriers in India – INS Vikramaditya from Russia & INS Viraat from UK

§  Puts India in the elite group of four nations – the US, Russia, the UK and France – in the world capable of designing and constructing aircraft carriers

 

INS Alleppey Decommissioned

§  Was one of the six Ponchicherry class coastal minesweepers, designed to detect and destroy underwater mines

TMT, SMAP, GOCE, MAST

Thirty Meter Telescope (TMT)

§  Mauna Kea volcano summit, in Hawaii; will be finished by 2020

§  Partner countries – India, US, Canada, Japan, China

§  Cost of the Project – $ 1.5 billion

 

Key Features of TMT

§  World’s largest infrared + optical telescope – because its primary mirror is 30 m wide.

§  Will help finding most distant and oldest stars that were born after Big Bang, Thus we can learn more about the origin of the universe

India’s contribution to TMT project

§  10% finance (1300 crore)

§  Mirror-coating & polishing of this telescope

§  Will develop the control system, sensors, fabrication, actuator systems

§  100 / 492 smaller, hexagonal mirrors, needed to build the 30m diameter primary mirror of the telescope

 

Indian astronomers will be allowed to use this telescope for the time proportional to India’s contribution (10%).  Japanese will get to use it for 25% and so on.

Soil Moisture Active Passive (SMAP) : NASA’s first satellite to collect global soil moisture

§  Designed to measure the moisture of Earth’s dirt accurately + a global map of the planet’s soil moisture levels every three days

§  Built to measure moisture in the top 2 inches of soil

 

Benefits of SMAP

§  To better forecast crop yields and assist in global famine early-warning systems

§  create more accurate weather models

§  learn more about drought conditions & even predict floods

 

Goce gravity boost to geothermal hunt

§  GOCE was the 1st of European satellites intended to map unprecedented detail the Earth’s gravity field.

§  It mapped Earth’s gravity field from 2009 to 2013 at high resolution.

§  Information about variations in gravity across the planet could help prospectors find promising locations where sub-surface heat can be exploited to generate electricity.

§  Goce’s maps are expected to shortcut some of the effort by pinpointing regions of the world with the best characteristics, such as where the continental crust is at its thinnest.

 

Geothermal energy is clean and sustainable heat from the Earth. This keen sensing is expected to narrow the search for prime spots to put future power stations.

Multi Application Solar Telescope (MAST)

§  Aimed at detailed study of the Solar activity including its magnetic field.

§  This study of solar activities would facilitate space weather predictions in the future.

§  Capable of capturing three-dimensional aspects of the solar magnetic fields further enabling the scientists to get a better understanding of the solar flares and eruptions taking place in such twisted magnetic fields.

§  USO is a part of Physical Research Laboratory (PRL), which is an autonomous unit of the Department of Space.

§  The observatory is situated on an island in the middle of Fatehsagar lake at Udaipur

 

Why observatory is made in the middle of lake? 

§  Large water body surrounding the telescopes decreases the amount of heating of the surface layers.

§  This decreases the turbulence in the air mass and thereby improves the image quality and seeing.

 

Features of MAST

§  50 cm aperture

§  Off-axis Gregorian-Coude telescope

 

Other Telescopes in India 

§  National Large Solar Telescope – proposed @Merak Village, Ladakh

§  ARIES Observatory –  Nainital

§  Solar Tunnel Telescope, Kodaikanal Solar Observatory @ Kodaikanal

India’s Three Stage Nuclear Programme

§  Was formulated by Dr. Homi Bhabha in the 1950s

§  India has 25% of world thorium reserves but only 1-2% global uranium reserve

§  it will enable the thorium reserves of India to be utilised in meeting the country’s energy requirements

 

Stage 1 – Pressurised Heavy Water Reactor

§  Natural uranium fuelled pressurised heavy water reactors (PHWR) produce electricity

§  Natural uranium contains only 0.7% of the fissile isotope uranium-235.

§  Most of the remaining 99.3% is uranium-238 which is not fissile but can be converted in a reactor to the fissile isotope plutonium-239

§  In PWHR, enrichment of Uranium to improve concentration of U-235 is not required. U-238 can be directly fed into the reactor core

§  Generate plutonium-239 as by-product [U-238 → Plutonium-239 + Heat]

§  Heavy water (deuterium oxide, D 2O) is used as moderator and coolant in PHWR

 

Stage 2 – Fast Breeder Reactor

§  Would use a mixed oxide (MOX) fuel made from plutonium-239, recovered by reprocessing spent fuel from the first stage, and natural uranium

§  plutonium-239 undergoes fission to produce energy, while the uranium-238 present in the mixed oxide fuel transmutes to additional plutonium-239

§  Thus, the Stage II FBRs are designed to “breed” more fuel than they consume

§  Uranium-235 and Plutonium-239 can sustain a chain reaction. But Uranium-238 cannot sustain a chain reaction, so it is transmuted to Plutonium-239

Stage 3 – Thorium Based Reactors

§  an advanced nuclear power system involves a self-sustaining series of thorium-232- uranium-233 fuelled reactors

§  This would be a thermal breeder reactor, which in principle can be refueled after its initial fuel charge using only naturally occurring thorium

 

According to the three-stage programme, Indian nuclear energy could grow to about 10 GW through PHWRs fueled by domestic uranium, and the growth above that would have to come from FBRs till about 50GW

Prototype Fast Breeder Reactor (PFBR)

Prototype Fast Breeder Reactor (PFBR)

§  Presently India is heading towards second stage of its nuclear programme

§  PFBR is a reactor, which produce more fuel than it consumes

§  PFBR is using uranium-238 not thorium, to breed new fissile material, in a sodium-cooled fast reactor design with no moderators required

 

Capacity 500 Mwe
Fuel Plutonium-Uranium oxide
Coolant Liquid sodium
Place Kalpakkam, Chennai
Built By Bharatiya Nabhikiya Vidyut Nigam Limited (BHAVINI)

§  Indira Gandhi Centre for Atomic Research (IGCAR) is responsible for the design of this reactor

§  500-MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam is getting ready to be commissioned in September.

§  It will signal India’s triumphant entry into the second stage of its three-stage nuclear power programme