Question # 1

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

de-Broglies hypthesis was experimentally verified by

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Maxwell

Compton

Einstein

Davison and Germer

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

Compton studied the scattering of x-rays by loosely bound electrons from:

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NaCl crystal

Graphite crystal

Zirconia

Copper crystal

None of these

From the theory of relativity, momentum p of the photon is related to energy as

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p = hfc

p = hf/c

p = f(hc,f)

p = cf/h

If you are moving at relativistic speed between two points that are a fixed distance apart, then the distance between the two points appers

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larger

shorter

equal

none of these

The positron was discovered by:

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In cosmic radiation

In 1932

By Carl Anderson

All above

By direc

the dilation of time applies to the timing processes which are:

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Physical

Chemical

Biological

All of these

None 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 threshold frequency of sodium is 6 x 10⁶MHz. The cut-off wavelength for this metal will be

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500 m

500 nm

500 km

500 cm

None of these

The ratio of energy E to the corresponding frequency (f) of the radiation (emitted or absorbed) is called:

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Wien's constant

Stefen's constnat

Planck's constant

Boltzmann's constant

None of these

Due to relative motion of observer and the frame of reference of events, time always:

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Dilates itself

Contracts itself

Stretches itself

Both (A) and (C)

None of these

The energy of a photon is represented by

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h/c²

h/T

hc²

hf/c²

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

Electromagnetic -radiation means:

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Photons

protons

Electrons

Mesons

None of these

The concept of direction is purely:

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Absolute

Relative

Relative to stars always

Relative to the sun always

None of these

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

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