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Current Affairs January 2024

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4

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

Correct Answer :

B. radiation from earth's surface


Related Questions

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4

The function of a moderator in a nuclear reactor is

A. to absorb unwanted neutrons

B. to slow down the fast neutrons to secure more effective hits on other nuclei

C. to decrease the number of fissile nuclei

D. to increase the number of fissile nuclei

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4

The velocity of sound in air

A. increases as the square root of the absolute temperature

B. decreases with temperature

C. is independent of temperature

D. None of these

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4

In the fuse of an electrical installation blows out

A. replace the fuse by a thin wire

B. replace the fuse by a thick copper wire

C. replace the fuse by a fuse wire of proper rating

D. replace the fuse by nichrome wire

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4

When the disturbed electrons of an exited atom transfer back into lower energy levels they emit energy in the form of electromagnetic wave pulses called

A. neutrons

B. electrons

C. phonons

D. photons

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4

A spherical mirror is

A. a reflecting elliptical portion

B. a reflecting spherical surface

C. a parabolic reflecting surface

D. a flat reflecting surface

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4

The numerical reading of the Fahrenheit thermometer of a given temperature

A. is proportional to that of the Celsius thermometer

B. is always greater than that of the Celsius thermometer

C. is always less than that of the Celsius thermometer

D. may be greater than or less than or equal to that of the Celsius thermometer

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4

The power of a lens is

A. equal to its focal length

B. equal to its radius of curvature

C. equal to the reciprocal of its focal length (in metres)

D. equal to twice its focal length

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4

Sound travels fastest in

A. air

B. water

C. iron

D. vacuum

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4

Dioptre is the unit of power of

A. convex mirrors

B. concave mirrors

C. concave lenses

D. lenses irrespective of types

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4

The principle of equivalence of mass and energy was established by

A. Dalton

B. Rutherford

C. Einstein

D. Planck

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4

Which of the following is not electromagnetic waves?

A. heat waves

B. sound waves

C. radio waves

D. light waves

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4

When light travels from one medium to another there is a change in its

A. velocity

B. wavelength

C. frequency

D. Both (a) and (b) above

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4

The planet with the reddish tinge is

A. Jupiter

B. Mars

C. Mercury

D. Saturn

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4

It is easier to climb down a staircase than climb up because in climbing down

A. work is done against gravity

B. the steepness of the staircase isn't felt

C. gravity assists

D. there is no friction between the legs and steps

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4

If an object is placed between two parallel plane mirrors, the number of images formed will be

A. 1

B. infinite

C. 0

D. 4

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4

Which of the following is fissionable?

A. U-234

B. U-235

C. U-238

D. Both (b) and (c)

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4

For detecting and, testing of small electric charges we use

A. an electrophorus

B. an electroscope

C. an electromagnet

D. an ammeter

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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

Body A is kept in contact with body B. Heat will flow from A to B if

A. the heat content of A is greater than that of B

B. the temperature of A is greater than that of B

C. the specific heat of A is greater than that of B

D. the specific heat of B is greater than that of A

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4

You want a supply of a small but constant current. Which of the following cells will you prefer?

A. Daniell cell

B. Leclanche cell

C. Dry cell

D. All the above

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4

If a man wants to hear clearly the echo of a sound produced by him from a hill, the hill should be away from him by a minimum distance of

A. 330 m

B. 33 m

C. 16.5 m

D. 165 m

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4

Halley's comet appears in the heavens once in

A. 40 years

B. 50 years

C. 76 years

D. 80 years

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4

Echoes are produced by

A. the reflection of sound waves

B. the refraction of sound waves

C. the interference of sound waves

D. reverberation of sound waves

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4

Like magnetic poles

A. attract each other

B. repel each other

C. neither attract nor repel

D. attract or repel depending upon the conditions

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4

The leader of the team who succeeded in constructing the first nuclear reactor (an atomic pile) in the world was

A. Albert Einstein

B. Enrico Fermi

C. HJ Bhabha

D. Sir Isaac Newton

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4

Gamma radiations are used for

A. sterilising food stuff

B. controlling pests

C. cancer therapy

D. All of these

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4

When the earth reaches its perihelion

A. it is nearest to the moon

B. it is nearest to the sun

C. it is nearest to Pluto

D. it is farthest from the sun

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4

When an electric apparatus is fitted with a three core flexible lead the insulation on the three wires is distinctively coloured. The present international convention is

A. brown for earth, yellow for live, light blue for neutral

B. green for earth, yellow for live, brown for neutral

C. yellow for earth, green for live, brown for neutral

D. brown or red for live, light blue or black for neutral and green or yellow for earth

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4

For an electron orbiting in a hydrogen atom, the necessary centripetal force keeping it in orbit is provided by

A. the electrical attraction between the negatively charged electron and the positively charged porton

B. the high speed of the electron

C. the low speed of the electron

D. gravity

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4

Moon has no atmosphere because

A. it has no population

B. it is quite far off

C. its surface is full of rocks

D. its gravity is not sufficient for any atmosphere to hold on to it