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Current Affairs January 2024

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4

The inside of both the walls of a thermos flask is silvered i.e., on the vacuum side in order to reduce heat loss by

A. convection

B. radiation

C. conduction

D. All the three

Correct Answer :

B. radiation


Related Questions

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4

The red colour of the setting sun is due to

A. the least scattered red colour reaching the eye

B. the dispersion of sun light occurred in air molecule in atmosphere

C. the diffraction of sunrays in atmospheric layers

D. interference of all the rays coming from the sun

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4

The maximum range of most TV signals is from 121 to 240 km only because

A. the curvature of earth limits the range of reception

B. the signals are weak

C. the signals are absorbed by air

D. the antennae are not powerful enough

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4

Air escaping rapidly from a narrow orifice in an inflated tyre feels cool because

A. the speed with which it escapes cools it down

B. of the higher temperature of the surroundings

C. of sudden expansion causing loss of internal energy

D. there is no real fall in temperature

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4

Tap water is placed in an open pad and allowed to evaporate. After some time the temperature of water

A. increases to a great extent

B. increases slightly

C. decreases slightly

D. decreases rapidly

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4

Why is nuclear fusion also known as thermonuclear reaction?

A. Fusion converts nuclear energy into heat

B. Fusion demands conditions of extremely high temperature to produce it

C. Fusion produces large amount of heat

D. Fusion reactions takes place in the sun

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4

In a hydraulic pressure

A. force on each square centimetre of the small piston is less than the force on each square centimetre of the large piston

B. the distance the small piston moves is equal to the distance the large piston moves

C. applied pressure is equally transmitted throughout the liquid in all directions

D. force acting on small piston is equal to the force acting on large piston

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4

Sound waves In 'air travel faster if

A. frequency is higher

B. wavelength is smaller

C. pitch is smaller

D. air is warmer

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4

Stars twinkle because of

A. refraction of light from them through air

B. reflection

C. absorption

D. All the above

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4

The colour of a star is an indication of its

A. distance from the earth

B. age

C. temperature

D. size

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4

The force of attraction or repulsion between two charged bodies is directly proportional to the product of the charges and inversely proportional to the square of distance between them. This was propounded by

A. Coulomb

B. Gilbert

C. Volta

D. Rutherford

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4

The heat generated in a conductor carrying current is proportional to

A. the resistance

B. the square of the current flowing through it

C. the time the current flows

D. All the above

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4

The largest planet in the solar system is

A. Neptune

B. Uranus

C. Jupiter

D. Saturn

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4

Sound travels fastest in

A. air

B. water

C. iron

D. vacuum

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An ohm is a unit of

A. potential difference

B. resistance

C. current

D. All the above

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The atmosphere gets heated up mainly by

A. direct sun's rays

B. radiation from earth's surface

C. radiogenic heat (resulting from radioactive decay)

D. cosmic rays coming from space

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4

A workman was working on a rail track. A young boy at a distance holds his ear close to the railway track. The boy was able to hear the sound of each blow or the workman twice. It is because

A. speed of sound is greater in steel than in air

B. speed of sound is greater in air than in steel

C. part of sound waves is reflected between rail tracks

D. the boy's ears are at a different distance from the source

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4

To produce beats it is necessary to have two waves

A. travelling in opposite direction

B. of slightly different frequencies

C. of equal wavelength

D. of equal amplitude

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4

When sound waves travel from one medium to another, the quantity which remains unchanged is its

A. speed

B. frequency

C. wavelength

D. All the above

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4

The brightest planet in the Solar System is

A. Jupiter

B. Mercury

C. Venus

D. Sirius

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4

A hydraulic brake in an automobile uses

A. a fluid to transmit the braking force

B. the force applied by the driver

C. hydrogen gas and not any liquid

D. a vacuum brake

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4

The period of a geostationary (synchronous) satellite orbiting the earth over the equator la

A. 16 hours

B. 12 hours

C. 20 hours

D. 24 hours

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4

The electroplating of a metallic article

A. protects the article from atmospheric corrosion

B. gives it a more attractive appearance

C. Both (a) and (b) above

D. None of the above

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4

Which of the following can produce electricity?

A. resistor

B. thermocouple

C. light bulb

D. neon tube

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4

In an oil lamp, holes are provided below the chimney so that

A. necessary oxygen for burning of oil may be provided

B. the convection current of air may be maintained to keep the lamp burning

C. the brightness of the lamp may be increased

D. All the above

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4

The characteristics of a musical note are

A. loudness

B. pitch

C. quality or timbre

D. All the above

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4

Velocity of sound in high altitudes is low because at such a height

A. the temperature is low

B. there is no air

C. the pressure is low

D. All the above

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4

The red colour of the setting sun is due to

A. the least scattered red colour reaching the eye

B. the dispersion of sun light occurred in air molecule in atmosphere

C. the diffraction of sunrays in atmospheric layers

D. interference of all the rays coming from the sun

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4

The escape velocity of a satellite projected from the surface of the earth is independent of

A. the mass of earth

B. the mass of the satellite

C. the radius of the earth

D. gravitation of the earth

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4

A solid ball of metal has a spherical cavity inside it. When the ball is heated the volume of the cavity will

A. increase

B. decrease

C. remain unaffected

D. have its shape changed

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4

Separating particles from a suspension is effected by

A. centrifugal force

B. frictional force

C. gravitational force

D. distillation