Question # 1

de-Broglies hypthesis was experimentally verified by

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Maxwell

Compton

Einstein

Davison and Germer

If a body reaches a speed equal to the speed of light, then its mass will became

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zero

very small

infinity

none of these

An intertial frame of reference is a frame of reference which is

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at rest

moving with uniform velocity

either at rest or moving with uniform velocity

none of these

Wien's constant is measured in:

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Metre per kelviin

Metre kelvin

Kelvin per meter

Joules

Dynes

The length contraction happens only

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Opposite to the direction of motion

along the direction of motion

perpendicular to the direction of motion

In any direction

When platinum wire is heated, then at the temperature of 500 ^oC, it becomes:

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Yellow

Orange red

Dull red

White

Cherry red

When monochromatic light is allowed to fall on cathode, it begins to emit electrons, these electrons are called

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thermoionic electrons

free electrons

photoelectrons

slow electrons

In order to produce pair production, a photon must have a energy

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0.511 Me v

0.256 Me v

1.02 Me v

0.956 Me v

The photoelectric effect, the maximum energy of photoelectrons depends on the

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particular metal surface

frequency of incident light

both of them

none of them

The inside cavity of the black body is

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painted white

painted silver

blackened with soot

painted red

If the radius of first orbit of hydrogen atom is 0.53° A the radius of second orbit will be

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2.120°A

0.212°A

21.2°A

0.14°

a

As the light shines on the metal surface, the electrons are ejected

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slowly

instantaneously

either of these

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

The mass of an object will be doubled at speed

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1.6 x 10⁸ms^-1

2.6 X 10⁸ms^-1

2.6 x 10⁷ms^-1

2.6 x 10⁹ms^-1

The year when A.H. compton was awarded Nobel Prize is:

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1923

1927

1931

1935

None of these

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

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

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