Question # 1

The positron was discovered by:

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In cosmic radiation

In 1932

By Carl Anderson

All above

By direc

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 unit of work function is:

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Joule

Electron volt

That of threshold frequency

Both (A) and (B)

None of these

G.P. Thomson observer experimentally that electrons and neutrons possess

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particle-like properties

wave-like properties

neither particle nor wave like properties

none of these

When a high energy photon interact with a metal, which of the following effect is most likely to be taken place

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pair production

photoelectric effect

Compton effect

None of these

The special theory of relatively treats the problems involving:

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Inertial frames of reference

Non-inertial frames

Non-accelerated frame

Botha (A) and (C)

Both (B) and (C)

The energy of the 4th orbit in hydrogen atom is

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2.5 ev

- 3.5 ev

-0.85 ev

-13.6 ev

S.I. unit of planks constant is

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J-s^-1

J.s

J.s^-2

J.s²

Photoelectric effect takes place with a photon of:

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Very high energy

Very low energy

Low energy

High energy

None of these

The value of the Stephen's constant for black body radiations is given by

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5.6 x 10⁸Wm^-2K^-4

5.67 x 10^-8Wm^-2K^-4

2.9 x 10^-3mK

2.9 x 10³mK

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

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Physical

Chemical

Biological

All of these

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

Wien's constant is measured in:

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Metre per kelviin

Metre kelvin

Kelvin per meter

Joules

Dynes

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

The speed of a pendulum is measured to be 3.0 s in the inertial reference frame of the pendulum. What is its period measured by an observer moving at a speed of 0.95 c with respect to the pendulum

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2.9 s

3.0 s

6.6 s

9.6 s

If A represents linear momentum and c, the velocity of light, then unit of pc in international system of units is:

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Newton

Joule

Joule-Sec

Joule-s^-1

Watt

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

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