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Current Affairs January 2024

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4

Hydrophone is an instrument used

A. for measuring relative density of liquids

B. by ships to pass on messages

C. for determining the depth of ocean bottoms etc.

D. by deaf people to aid hearing

Correct Answer :

C. for determining the depth of ocean bottoms etc.


Related Questions

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The maximum displacement of the particle in a mechanical wave motion is known as

A. amplitude

B. vibration

C. frequency

D. phase

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4

Mica is used in an electric iron because it is a

A. good conductor of heat

B. good conductor of electricity

C. bad conductor of electricity

D. Both (a) and (b) above

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4

Among the following the most suitable material for the core of an electro-magnet is

A. steel

B. wood

C. soft iron

D. copper

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4

The star nearest to the sun is

A. Proxima Centauri

B. Sirius

C. Aldebaran

D. Vega

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4

The unit of power in SI is

A. Joule

B. Newton

C. Joule/Sec

D. Erg/Sec

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In a longitudinal wave, the direction of propagation of the wave is

A. the same as the direction of the vibrations of the vibrating body

B. at right angles to the direction of the vibrations of the vibrating body

C. Both (a) and (b) above

D. None of the above

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4

When a steel ball is placed on the surface of mercury, it does not sink because

A. of the surface tension of mercury

B. mercury is a semi-solid

C. of the high viscosity of mercury

D. the density of mercury is greater than that of steel

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4

Ultrasonic waves are used

A. in medical and surgical diagnosis

B. in testing the quality of the linings and pads used in vehicles and aircraft brakes

C. to clean surgical instruments, jewellery and similar articles

D. All the above

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4

A boy sitting in a train moving with a uniform velocity drops a coin outside. A man standing outside the train will find the trajectory of the coin to be

A. a parabola

B. a horizontal straight line

C. a vertical straight line

D. a circle

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4

Besides protons, the nucleus of an atom contains

A. electrons

B. neutrons

C. neutrons and electrons

D. electrons, neutrons and other particles

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4

In the visible spectrum which colour has the shortest wavelength?

A. Red

B. Blue

C. Yellow

D. Violet

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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

Which of the following rays has the highest penetrative power?

A. a -rays

B. � -rays

C. ? -rays

D. X-rays

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4

The completely dark portion of a shadow of an object is known as

A. umbra

B. penumbra

C. image

D. black portion of light

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4

Ultrasonic waves are used

A. in medical and surgical diagnosis

B. in testing the quality of the linings and pads used in vehicles and aircraft brakes

C. to clean surgical instruments, jewellery and similar articles

D. All the above

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4

Who first established the fact that the earth revolves round the sun?

A. Sir Isaac Newton

B. Kepler

C. Copernicus

D. Ptolemy

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4

Mercury does not stick to glass because

A. cohesive forces between the mercury molecules are greater than adhesive forces between mercury and glass molecules

B. the adhesive forces between mercury and glass molecules are greater than the cohesive forces

C. both the cohesive and adhesive forces are equal

D. None of the above

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4

The air inside an electric, bulb is removed to prevent

A. oxidation of the tungsten filament

B. bursting of the bulb

C. loss of light due to absorption

D. keeping the weight of the bulb less

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4

Formation of shadows can be explained by

A. rectilinear propagation of light

B. reflection

C. refraction

D. total internal reflection

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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

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 world's first artificial satellite Sputnik I was launched by Russia in

A. 1985

B. 1957

C. 1959

D. 1960

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4

When a body is projected upwards

A. the time for the upward journey and downward journey are the same

B. the upward journey takes more time

C. the downward journey takes more time

D. Can't be said

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4

Radio waves sent out by radio stations are reflected by

A. troposphere

B. stratosphere

C. mesosphere

D. ionosphere

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4

Solids have definite shapes. This is because

A. the forces of cohesion of the molecules within are very much less in them

B. the forces of cohesion are very large

C. the forces of adhesion are large

D. the forces of adhesion are less

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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

Choose the correct answer

A. Microphone converts sound energy into electrical energy.

B. Electric fan converts electrical energy into mechanical energy.

C. Battery converts chemical energy into electrical energy.

D. All the above

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4

The stars that shine brightly then dimly and then brightly are known as

A. meteors

B. binaries

C. variable stars

D. bright stars

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4

The body of an electrical appliance is earthed in order that

A. electricity may not leak

B. there may be smooth flow of electricity

C. a short circuit may be prevented

D. current may pass to the earth in case of a short circuit without doing any harm to the person

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4

At temperature near OK, (zero kelvin) metals such as lead and tin become

A. insulators

B. semiconductors

C. superconductors

D. condenser