1.     Weight is max. at: Poles  Minimum at: Equator.

                              2.     Escape Velocity is 25000 miles/hour (11.2 k.m./second)

                               3.     Rainbow is the result of: Diffusion & Total Internal Reflection.

4.     T.V. remote uses Radio Waves.

5.     When light Travels from Air to Glass: Wave Length & Velocity is affected while Frequency remains Unchanged.

6.     Electric Fuse: made of the substance of Low melting point, high specific resistance, is put in series connection.

7.     Pure Hydrogen: is used as Rocket Fuel because of its high heat capacity per unit weight.

8.     The roof is blown away when high-speed air gushed into Close room: Following Bernoulli's Law.

9.     Electric Wiring: Brown/Red- live, Blue/Black- Neutral, Green- Ground;

10. Comet's Tail points always away from Sun.

11. Law of Cooling was given by Newton, it says substance with higher temperature has a higher rate of cooling.

12. Simple Harmonic Motion: Amplitude- the distance covered, Wavelength-the distance between two oscillating points.

13. Sound Waves: Humans can hear so

14. Audible sounds is in the range of 20-20000kHz.

15. Dogs, cats & Bats can hear Sound of the Higher frequency range.

16. The impact of sound remains up to 1/10 of a second.

17. During Night we can hear to longer.

18. Intensity of Sound tell of weak or Strong sound.

19. Watt is 4.186 J

20. 1 BTU is 256 cal.

21. Kirchoff's Law: A good absorber is a good Emitter.

22. Convex Lens: +ve Power, Concave Lens: -ve Power.

23. Light reaches to us from Sun: 8 minutes & 19 seconds, while from the moon: 1.28 seconds.

24. Astigmatism: an ailment in which the affected person can see horizontally but not vertically.

25. Change of medium by light, then, change in Amplitude & Velocity only not in frequency.

26. Cosmic Ray Intensity: Minimum at the magnetic Equator.

27.  Yellow Head Lights are prescribed for automobiles because Yellow penetrates fog and provides better visibility.

28. The best conductor of Heat & Electricity is Mercury.

29. Centrifugal Force is felt at the Equator.

30. A best lubricator posses least Viscocity

31. The value of 'g' is maximum at Poles.

32. Soaps bubbles show colors because of: Interference.

33. Red Light is used in the Photographer's room.

34. 50 Hzs means passing of bob to and fro of the center 50 times.

35. Air Bubbles acts as Concave lens.

36. Rockets are launched with a velocity of 1600 KM/HOUR.

37. Impurity in Liquid increases Boiling Point.

38. Hot water extinguishes quickly than a cooler one.

39. LIGHT: Intensity of light depends on -Amplitude, Color of Light-Frequency, Velocity of The light- refractive index of the medium.

40. Concave Lens: is a diverging lens, so used for Persons with Short Sightness.

41. 1 Knot is 1.852 km/hour, I nautical mile means 1.158 miles or 1.852 km.

42. Ton in ACs tells of their cooling capacity.

43. Siren of Police Van: Lowers in Pitch.if coming nearer

44. When a magnet bar is suspended, them, N inclines always to ground.

45. Kerosene oil is Used as Jet Fuel

46. Center of gravity plays a significant role in: Racing Cars, Double Deck Buses, Lamp Stand etc.

47. Barometer: Falls Suddenly indicates – Storm, Gradual Increase-Fair weather, Gradual Fall- Rain,

48. Archimedes Principle: the weight of water spilled is equal to the weight of the object submerged.

49. Ice is lesser dense than water.

50. AdhesionAttraction between unlike Molecules &

51. Cohesion: Attraction between like molecules.

52. Density of Sea water > River Water.

53. Speed of flowing water is greater bottom.

54. ‘g’ is Poles & Min. at the Equator.

55. Geo stationery Sattelite orbits at: 35000 km.

56. When the lift moves UP: weight  is High Lift comes down: weight is low

57. Rolling of Heavier The object gives more friction.

58. The viscosity of water decreases with increase in Pressure which is a contradiction to other liquids.

59. Temperature of a Healthy person: 98.4 F say 36.9 degree C.

60. Temperature  Report is prepared by using Six’s Max/min thermometer.

61. Bimetal Strip(made of Brass & Invar): acts as Thermostat switch.

62. Water at 4 degrees C has min volume max density.

63. Rough Surface is better absorber surface, Emitter

64. Newton’s law of Cooling: Rate of cooling is directly proportional to Their Temperature difference(environment & the object)

65. Hotter objects take lesser time than comparatively cooler.

66. Cloudy Nights are warmer.

67. 1 calorie = 4.2 J

68. 1 Calorie is the amount of heat required to raise the temperature of 1 gram of water by 1 degree C.

69. Light is a transverse wave.

70. Sound is a Longitudinal wave.

71. The velocity of light is: Frequency * Wavelength.

72. Human Voice comes from the vibration of the vocal chord in Larynx.

73. Pitch(shrillness) is Loudness depends on Frequency.

74. Speed of Sound (in dry air, Temperature-0 degree C) 331 m/s

75. Water vapor presence increases Speed.

76. Echo of sound comes after 0.1 seconds, distance- 17 meters

77. Prolonging of Sound by reflection is called Reverberation

78. Sonar is used to measure the depth of the water body & To locate the submerged object.

79. Ultra-Sonic is used to detect the flaws in interiors of Solids, destroy microorganism & mapping underground structure for Oil & mineral deposits.

80. Bats use Ultra-Sonic the get the guide to path.

81. Refraction of Sound is caused by Different characteristics of air Layers in Atmosphere.

82. Warm Air facilitates sound to move faster & Also tends it to bend away from ground.

83. Cooler Air does the opposite, So Sound can be heard at longer as Sound doesn’t move away from ground.

84. Increase of Amplitude of Sound is called Resonance

85. Doppler Effect Tells of effect in the frequency of a sound source,

1)If frequency increases imply source is approaching closer 2)If frequency decreases that means the source is moving away.(REDSHIFT)

86. Magnetic Substances: Iron, Cobalt & Nikel.

87. Declination: The magnet bar doesn’t lie an exact N-S but makes an angle with horizontal, this angle is called Dip.

88. Dip remains 0 degree at Equator & 90 degrees at poles.

89. Electric Charge tends to concentrate at a Pointed End.

90. Ceramics behave like Superconductors at 100 K.

91. Semi-conductors are insulators in their Pure state but Turn into conductors with the addition of some impurities like Si, Ge..

92. Power Transmission- Power is generated & sent to sub-Power stations at 132 KV then stepped down to 33KV, then again stepped down to 220 V to send it to consumers.

93. Effective Value of The power that comes to consumers is 200 V while Peak Value is 311 V.

94. In 2 wire transmission, 2 wires are Live & Neutral while in 3 wire transmission, wires are Live, Neutral & Earth wire.

95. Fuse uses an alloy of Tin & Lead, the same alloy is used in Soldering in Electronics etc.

96. Fluorescent Tube has Hg in low pressure. It gives out Ultra Violet Rays, which fall on the coating on the tube that emits visible light.

97. Refraction When light moves from one medium to another then speed of light gets altered, hence the path doesn’t remain straight line. There are 2 cases, 1)When light moves from dense to rare, It moves away from normal, 2) when light moves from rare to dense medium, It moves towards normal.

98. Atmospheric Refraction occurs because the density of air decreases with altitude.It causes:1) Sun is seen even after sunset. 2)When Sun/Moon are near to horizontal, they look like elliptical. 3) Twinkling of Stars is caused due to atmospheric Refraction.

99. MirageThis occurs in Hot deserts.

100.                 Total Internal Refraction: It happens when the angle of incidence is greater than Critical Angle.

101.                 Rainbow is caused by Dispersion of Sun Light. In Rainbow, we have Red at Top(Constituent of Sunlight with Minimum Frequency but Maximum Wavelength, hence, least deviation of the path, so remains at the top) while Violet(max. frequency, min wavelength) at the bottom.

102.                 In Vacuum, all colors move with the same velocity.

103.                 Complementary ColorsTwo colors which when mixed give white color.



2.     1. Why water is used in hot water bags: because the water has high specific heat. Thus it takes more time to cool down

3.     2. A body absorbs the maximum amount of heat when it is: Black & Rough surface; Best reflectors – White & smooth surface

3. The temperature of a liquid is 32ºF what is the temperature in Celsius scale: 0ºC

4. The temperature at which the reading of both the Fahrenheit scale and Celsius scale are the same: at – 40º both Fahrenheit and Celsius scale show same reading

5. How the refrigerator protects the food from contamination: at low temperature, germs cannot multiply and thus become non-reactive

6. What is Relative humidity: Relative humidity is the ratio of water vapor density to the saturation water vapor density and expressed in percentage ActualvapourDensity RelativeHumidity= ×100 SaturationVapourDensity

7. Why sound wave cannot be transmitted through vacuum: A sound wave is a longitudinal wave. Hence it requires a material medium for its propagation

8. Ultrasonic waves cannot be polarized: Ultrasonic waves are sound waves. Sound waves are longitudinal waves cannot be polarized. 

9. Coolidge tube is used to produce: Coolidge tube is a vacuum tube that is used in the production of X-rays.

10. Why red colour of light deviates least through the prism: The smaller the wavelength the larger will be the deviation (refraction). As the red light has the largest wavelength, it deviates the least.

11. The unit of activity of a radioactive source is Becquerel.

• One Becquerel is defined as the activity of a quantity of the radioactive substance in which one nucleus decays per second,

 it is named after the great scientist Henry Becquerel.

12. What is the SI Unit of measurement of Angle: Radian

13. What is the SI Unit of Inductance: Henry.

14. What is the unit of Refractive index: dimensionless

 • Because it is defined as how fast light travels through a material i.e RF= c/v, where c is the speed of light in vacuum and

v is the phase velocity of light in the medium. Hence the ration c/v comes out to be dimensionless.

15. Magnification is basically: the ratio of the height of an image relative to the height of the object.

16. Natural magnet is also called as: Lodestone.

 ● A lodestone is a naturally magnetized piece of the mineral magnetite. Lodestone a permanent magnet mineral.

17. Which layer of the earth’s atmosphere reflect back the radio waves to the earth’s surface: Ionosphere

18. Cycles per second is the unit of: EMW, Cycles per second is an alternative unit for the frequency of an Electromagnetic wave

• The other unit for frequency is Hertz

19. The concept of electromagnetic waves was introduced by: Maxwell

* Electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light.

20. Insects can move on water: due to surface tension of water

• Due to the surface tension, the free surface of water behaves like a stretched elastic membrane which is able to support the small weight of insects and they can move on the surface of water.

21. If a liquid wets a solid surface, the angle of contact between them will be: less than 90 degrees.

• When the angle of contact between the liquid and a solid surface is acute, the liquid is said to wet the surface. If there are impurities in liquid, then they can alter the values of the angle of contact.

22. The resistance of a conductor is directly proportional to: length

23. What is the unit to measure the intensity of sound: Decibel

24. What is mass per unit volume: Density

25. A spoon which seems tilted in water, is an example of: Refraction

26. ‘Ohm’ is the unit of: Resistance.

•The ohm is defined as an electrical resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere, the conductor not being the seat of any electromotive force.

27. Rotation of the earth causes deflection of wind by: Coriolis Effect

28. A moving body definitely possesses- Kinetic Energy

● Potential Energy- is possessed by height or elevation of a body.

● Mechanical Energy- is defined as the ability to do work.

● Heat Energy- Possessed due to the movement of tiny particles caused by temperature. 

29. Water droplets cause rainbow due to: reflection & refraction of sunlight.

30. Steel is more elastic than rubber because: Elasticity is the property of being stretched and restored after the removal of stress (force).

Steel restores quickly as compared to


rubber under a given limit of stress   

4.     Few more..

5.     1. Work = force × distance
कार्य = बल × दूरी

2. Energy = force × distance

ऊर्जा = बल × दूरी

3. Speed = distance / time

गति = दूरी / समय

4. Velocity= displacement / time

वेग = विस्थापन / समय

5. Electric field = electrical force/charge

विद्युत क्षेत्र= वैद्युत बल/आवेश

6. Force = force/area


7. Volume = length × width × height

आयतन = लंबाई × चौड़ाई × ऊंचाई

8. Mass density = mass/volume

द्रव्यमान घनत्व =द्रव्यमान/आयतन

9. Acceleration =velocity / time

त्वरण = वेग / समय

10. Power = work / time

शक्ति = कार्य / समय

11. Pressure = force / area

दाब =बल/क्षेत्रफल

11. Momentum = mass × velocity

संवेग = द्रव्यमान × वेग

13. Area (A) = Length × Width

क्षेत्रफल ( A ) = लम्बाई × चौड़ाई

14. Force (F) = Mass × Acceleration

बल ( F ) = द्रव्यमान × त्वरण

15. Pressure Energy = Pressure × Volume

दाब ऊर्जा = दाब × आयतन

16. Impulse = force × time

आवेग = बल × समय

17. Linear momentum = mass × velocity

रैखिक संवेग = द्रव्यमान × वेग

18. Kinetic energy = 1/2 mv²

गतिज ऊर्जा = 1/2 mv²

19. Mechanical energy = kinetic energy + potential energy

यांत्रिक ऊर्जा = गतिज ऊर्जा + स्थितिज ऊर्जा

20. Angular momentum = Inertial × Angular velocity

कोणीय संवेग = जड़त्वाघूर्ण × कोणीय वेग