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prelims GK > physics > Flashcards

physics Flashcards

1
Q

What is the SI unit for measuring intensity of ‘sound or ‘Noise™?

A

Decibel

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2
Q

What principle/law explains the working of the hydraulic brakes in automobiles?

A

Pascal’s law

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3
Q

Name the process of production of energy in the Sun

A

Nuclear fusion

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4
Q

The type of mirror used in automobiles to see the
traffic on the rear side is

A

Convex

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5
Q

The sun heats the earth through:

A

Radiation

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6
Q

Which one of the following has the highest value of
specific heat and used in a “hot water bag” and “car
radiator”?

A

Water

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7
Q

At what temperature (in degree Celsius), the numerical values on Celsius and Fahrenheit scales become equal?

A

-40

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8
Q

Instrument used to measure the force, velocity and speed of the wind is

A

Anemometer

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9
Q

Which animals use ultrasonic sound to catch their
prey and avoid obstacles?

A

Bats

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10
Q

The oil in the wick of an oil lamp rises up due to:

A

Capillary action

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11
Q

What type of lens is used to correct vision of a person suffering from Myopia or near sightedness or ‘Short- sight?

A

Concave lens

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12
Q

lens [#R-5, TCS|
What is the SI unit of temperature?

A

Kelvin

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13
Q

dynamo is used to convert

A

:- Mechanical energy into electrical energy

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14
Q

Name the device that measures the distance travelled by a vehicle

A

Odometer

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15
Q

A is an electrical device that converts alternating current to direct current which flows only in one direction.

A

rectifier

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16
Q

Twinkling of stars is mainly due to which phenomena?

A

Refraction of light by atmosphere

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17
Q

The blue colour of sky is due to

A

scattering of shorter wavelengths of sunlight in
the atmosphere

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18
Q

Fiber-optic cable used in communication, works on the principle of

A

total internal reflection of light

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19
Q

Ozone layer above the surface of Earth provides a
shield against

A

Ultra-violet rays

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20
Q

Calculate the time period (in seconds) of asound wave of wavelength 2m travelling with a speed of 250 m/s.

A

0.008

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21
Q

Calculate the pressure (in Pa) if a thrust of 750 N is applied to an area of 5 m2.

A

150pa

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22
Q

Find the acceleration (in m/s?) produced in a body of mass 10 kg when a force of 20 N is applied on it

A

2

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23
Q

The audible range of sound for an average adult human
being is

A

20 Hz - 20000 Hz

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24
Q

What is the resistance (in Q) of an electrical compo- nent if a current of 0.4 A passes through it on application of 12 V of potential difference across it?

A

30

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25
Q

A body of mass 3 kg accelerates from 10 m/s to 20
m/s in 5 seconds due to the application of a force on
it. Calculate the magnitude of this force (in N).

A

6

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26
Q

Due to an acceleration of 1 m/s? the velocity of a body increases from 15 m/s to 20 m/s in a certain period. Find the displacement (in m) of the body in that peri- od.

A

87.5

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27
Q

The splitting of white light into its constituent colours. by a triangular prism is called

A

Dispersion of light

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28
Q

A light year is a measure of

A

Distance

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29
Q

is a scalar quantity.

A

Electric current / Speed / Powe

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30
Q

Hertz is the SI unit of

A

Frequency

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31
Q

A is a safety device which limit the current, prevents damages to electrical circuits and possible fires

A

Fuse

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32
Q

has the same dimension as that of linear mo- mentum?

A

Impulse

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33
Q

The Newton’s First Law is also called as

A

Law of inertia

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34
Q

The SI unit of acceleration is

A

m/s2

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35
Q

Quantitatively, the inertia of an object is measured by
its

A

Mass

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36
Q

Which electromagnetic radiation is used for artificial
satellite communication?

A

Microwave

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37
Q

What is the SI unit for electrical resistance?

A

Ohm

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38
Q

What is the SI unit of pressure?

A

Pascal

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39
Q

Speed of sound in air is unaffected by change in:

A

Pressure

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40
Q

The reason for a swimming pool to appear less deep than the actual depth is

A

Refraction

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41
Q

Hygrometer is a device which is used to measure

A

Relative humidity

42
Q

In 1662, ____________ formulated a fundamental law in gas
dynamics named _____________ , which concluded that for a given mass of gas at constant temperature, the volume
of the gas varies inversely with its pressure. This law,
expressed through the equation P1V1 = P2V2, demonstrates that when a gas is compressed in an enclosed
space, its volume decreases while the pressure it exerts on the container increases.

A

Robert Boyle, Boyle’s Law

43
Q

Which of the metals has the maximum thermal/elec- trical conductivity?

A

Silver

44
Q

The instrument which uses sound waves to measure
the depth of oceans is

A

Sonar

45
Q

In which of the following mediums, speed of the sound
will be maximum?

A

Steel

46
Q

A solid needle placed horizontally on the surface of the
water floats due to

A

surface tension of water

47
Q

During ________________ ‘motion of an object along a straight line,
the velocity remains constant with time.

A

Uniform

48
Q

Find the work done (in J) when a charge of 24 C moves across a potential difference of 6 V.

A

144 (W=VQ — 624 — 144)

49
Q

Find the acceleration (in m/s?) of a body which accel- erates from 10 m/s to 20 m/s in 4 seconds.

A

2.5

50
Q

The sound waves having frequencies less than ___________
Hz are called infrasonic waves.

A

20

51
Q

What is the value of the Least Distance of Distinct vi- sion (in cm) for a normal human being?

A

25

52
Q

A Sonar of a ship sends sounds waves of speed 1500 m/s. These waves are reflected back by the ocean floor in 5 seconds. Find the depth (in m) of the ocean floor.

A

3750

53
Q

Find the potential energy gained by a body of mass 60 kg, if it is raised by 12 m.

A

7200

The potential energy (PE) gained by a body of mass (m) raised to a height (h) is given by the formula:
PE = m * g * h

54
Q

How many watts are there in a horsepower?

A

746 watts

55
Q

What is the effective resistance (in Q) of two resistors
12 Q and 24 Q connected in parallel?

A

8

56
Q

What is the heat generated (in J) in a heating element
of resistance 900 Q when a current of 0.3 A passes through it for 10 seconds?

A

810

H = I² * R * t

57
Q

The instrument used to measure either direct or alter- nating electric current in amperes is called:

A

ammeter

58
Q

What is the SI unit of electric current

A

Ampere

59
Q

“Parsec” is the unit measurement of

A

Astronomical distance

60
Q

Which scientific instrument is used to measure atmospheric pressure?

A

Barometer

61
Q

What is the SI unit for measuring the luminous inten- sity

A

Candela

62
Q

When milk is churned, the cream separates from it due to:

A

Centrifugal force

63
Q

Which lens always forms a virtual, erect and dimin- ished image?

A

Concave

64
Q

Which mirror is used by doctors for examining eyes,
ears, nose, throat and teeth?

A

Concave mirror

65
Q

On the basis of which phenomenon does the Jet Engine work?

A

Conservation of Linear Momentum

66
Q

What is the SI unit of lens capacity?

A

Dioptre

67
Q

Kilowatt hour (kWh) represents the unit of

A

Energy

68
Q

Which is the highest-frequency (minimum wavelength) electromagnetic waves?

A

Gamma Rays

69
Q

Which is a bad Thermal Conductor (good insulator)

A

Glass

70
Q

A Fuse wire is characterised by

A

High resistance and low melting point

71
Q

Amount of water vapour (moisture in air) in the atmosphere is measured in terms of

A

Humidity

72
Q

Which is the first known instrument to measure the humidity of air or gas, built by Leonardo da Vinci
around 1400?

A

Hygrometer

73
Q

Rainbows are produced when sunlight:

A

Incident on rain drops hanging in the atmosphere is dispersed after suffering refraction and internal reflection.

74
Q

A metal plate with a circular hole at the centre is heated. What will happen to the area of the hole?

A

Increases

75
Q

The device which converts sound energy into electrical energy is called

A

Microphone

76
Q

The phenomenon of change in direction of light when
it passes from one medium to another is called

A

Refraction

77
Q

The colour of the clear sky is blue due to the phenomenon of:

A

scattering of light

78
Q

The “laws of vibrating string” can be studied by

A

Sonometer

79
Q

Heat flows as a result of difference of

A

Temperature

80
Q

The colours of stars depend on their

A

Temperature

81
Q

The first law of thermodynamics is simply the case of

A

The law of conservation of energy

82
Q

The filament of electric bulb is made up of

A

Tungsten

83
Q

A small drop of oil spreads over water because:

A

water has a higher surface tension

84
Q

A bullet of mass 10gm is fired with a velocity of 40 m/s from a gun of mass 8 kg. Find the recoil velocity (in m/s) of the gun.

A

0.05 (0.01 * 40/8)

85
Q

1 Micron is equal to

A

10^-6m

86
Q

Escape velocity at the earth’s surface is

A

11.2 km/s

87
Q

Find the kinetic energy (in J) possessed by a body of mass 10 kg moving with a velocity of 5 m/s.

A

125

KE = 1/2 * m * v^2

88
Q

What is the heat released by a heating filament rated
24 W when it is kept on for 6 seconds?

A

Heat (Q) = Power (P) * Time (t)

144

89
Q

68 degree Fahrenheit is equal to how many degrees Centigrade?

A

Celsius = (Fahrenheit - 32) * 5/9

20

90
Q

Find the current (in A) when a charge of 500 Coulomb flows in 25 seconds.

A

20

91
Q

A body of mass 8 kg is moving with a velocity of 4m/s,
find its momentum.

A

32

92
Q

Water has maximum density of 1 g/cc at

A

4 degree celsius

93
Q

Find the resistance (in mega ) of awire of length 20m,
cross sectional area 1 cm? and made of a material of resistivity 200 Qm.

A

R = ρ * L / A

40

94
Q

The angle in which a cricket ball should be hit to travel
maximum horizontal distance is:

A

45° with horizontal

95
Q

If the acceleration due to gravity on the surface of earth
is g, then the acceleration due to gravity on the surface
of a planet whose mass is same as that of earth and
radius is half as that of earth is _________

A

The acceleration due to gravity (g) is given by the formula:

g = GM / r^2

4g

96
Q

What is value of G (gravitational constant) in F =Gm1m2/r?

A

6.672 x10^-11 N m2 kg ^-2

97
Q

Calculate the frequency (in Hz) of a sound wave of wavelength 5 m travelling with a speed of 360 m/s.

A

72

98
Q

What is the power rating (in W) of a bulb if a current of 0.3 A passes through on application of 240 V of poten- tial difference across its terminals?

A

72

Power = (Current)^2 * Resistance

v=I R

99
Q

A body is initially moving with a velocity of 10 m/s It undergoes an acceleration of 2 m/s for 5 seconds Find the displacement (in m) of this body in these 5 seconds.

A

75

100
Q

A galvanometer can be converted to a voltmeter by connecting

A

high resistance in series

prelims GK (12 decks)

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