Question # 1

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 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 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

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 energy of a photon in a beam of infrared radiation of wavelength 1240 nm is

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100 ev

10⁶e v

10³e v

1.0 e v

The concept of direction is purely:

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Absolute

Relative

Relative to stars always

Relative to the sun always

None of these

In photoelectric effect the energy of ejected electrons depend on

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The frequency

The intensity

Both frequency and intensity

None of these

Which one of the following physical quantities changes with relativistic speed

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Length

Mass

Time

All of the above

Photoelectrons are emitted when ultraviolet light falls on:

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Casium

Silver

Potassium

Any of these

None of these

Which of the following phenomenon proves the particle nature of light

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interference

diffraction

photoelectric effect

none of these

Max plank received the Nobel Prize in physics for his discovery of energy quanta in

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1900

1906

1912

1918

The energy of a photon is represented by

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h/c²

h/T

hc²

hf/c²

The unit of work function is:

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Joule

Electron volt

That of threshold frequency

Both (A) and (B)

None of these

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

With the help of 50 K v electron microscope, a resolution of

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0.5 to 1 m to possible

1 m to 10 m is possible

0.5 to 1 nm is possible

1 to 10 nm is possible

There is certain frequency below which no electrons are emitted from the metal surface, this frequency is known as

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maximum frequency

minimum frequency

threshold frequency

all of these

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

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