Question # 1

At the temperature, a body emits radiation which is principally

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of long wavelengths in the visible region

of long wavelengths in the invisible infrared region

of short wavelength in invisible ultraviolet region

none of these

The analysis of the distribution of wavelengths of the radiation emitted from a hot body set the foundation of new mechanics, known as

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classical mechanics

Newtonian mechanics

quantum mechanics

statistical mechanics

Photocell is a device which converts

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chemical energy into electrical energy

electrical energy into light energy

heat energy into electrical energy

light energy into electrical energy

An inertial frame is that frame in which

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a>0

a=0

a<0

none of these

Momentum is a parameter associated with

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wave motion

particle motion

neither wave nor particle motion

none of these

According to the de-Brogile relation, an object of large mass and ordinary speed has

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very small wavelength

very large wavelength

very small frequency

all of these

Intensity of light determines the:

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Energy of each photon

Number of photons

Speed of photons

Size of photons

None of these

The mass 'm' of a body moving at 0.8 c (whose rest mass is mo) becomes

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2 mo

1.67 mo

0.67 mo

2.67 mo

According to the electromagnetic wave theory of light, increasing the intensity of incident light should increase the

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number of photoelectrons

size of the photoelectrons

charge on photoelectrons

K.E of photoelectrons

According to Einstein, with the great increase in the speed of the body the relativistic length of the body

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Remains constant

Decreases

Increases

Reduces to zero

If a material object moves with the speed of light 'C' its mass becomes

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Equal to its rest mass

Four times of its rest mass

Double of its rest mass

Infinite

The location and speed anywhere on earth can now be determined using relativistic effects by NAVISTAR to an accuracy of

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2 cm/s

20 cm/s

200 cm/s

2000 cm/s

When the atomic particle are moving with velocities approaching that of light:

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Newton's laws become valid

Relativistic effects become prominent

Botha(A) and (B) are valid

Neither (A)nor (B)

There mass becomes zero.

As compared to the distance measured by an observer on Earth, the distance from Earth to a star measured by an observer in a moving spaceship would seem:

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Smaller

Lerger

Same

Much larger

None of these

A particle of mass 5.0 mg moves with a speed of 8.0 m/s. Its de-Brogile wavelength is

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1.66 m

1.66 x 10^-10m

1.66 x 10^-29cm

1.66 x 10^-29m

The special theory of relativity is based on the

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one postulate

two postulates

three postulates

four postulates

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ECAT Physics Chapter 19 Dawn of Modern Physics Online Test MCQs With Answers

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