EASY

Earn 100

For photoelectric effect which of the following statements are true.
I) The kinetic energies of the photoelectrons do not depend on the frequency of light
II) Photoelectric effect will always occur for highly intense light
III) The maximum kinetic energy of photoelectron does not depend upon the intensity of the light
IV) The escaping electron's kinetic energy is larger for larger frequency

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Important Questions on Dual Nature of Matter and Radiation

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

Radiation of wavelength

λ

is incident on a photocell. The fastest emitted photoelectron has a speed

v

. If the wavelength is changed to

\frac{3 λ}{4}

, the speed of the fastest emitted photoelectron will be

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

When a certain metallic surface is illuminated with monochromatic light of wavelength

λ,

the stopping potential for photoelectric current is

3 V_{0}

and when the same surface is illuminated with light of wavelength

2 λ,

the stopping potential is

V_{0} .

The threshold wavelength of this surface for photoelectric effect is

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

A pulse of light of duration

100 ns

is absorbed completely by a small object initially at rest. Power of the pulse is

30 mW

and the speed of light is

3 \times 10^{8} m s^{- 1}

. The final momentum of the object is

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

A photoelectric material having work-function

ϕ_{0}

is illuminated with a light of wavelength

λ (λ < \frac{h c}{ϕ_{0}})

. The fastest photoelectron has a de Broglie wavelength

λ_{d}

. A change in wavelength of the incident light by

Δ λ

results in a change

Δ λ_{d}

λ_{d}

. The ratio

\frac{Δ λ_{d}}{Δ λ}

is proportional to

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

Light of wavelength

500 nm

is incident on a metal with work function

2.28 eV.

The de Broglie wavelength of the emitted electron is:

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

A photoelectric surface is illuminated successively by monochromatic light of wavelengths

λ and \frac{λ}{2} .

If the maximum kinetic energy of the emitted photoelectrons in the second case is

3

times that in the first case, the work function of the surface is :

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

Photons with energy of

5 eV

are incident on a cathode,

C

in a photoelectric cell. The maximum energy of emitted photoelectrons is

2 eV.

When photons of energy

6 eV

are incident on

C

, no photoelectrons will reach the anode,

A

, if, the stopping potential of

A

relative to

C

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

The graph between maximum kinetic energy and intensity of light in photoelectric effect is plotted. Out of the four graphs $A, B, C, D$ shown in the figure, the correct graph is

Question Image

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

In a photoelectric effect measurement, the stopping potential for a given metal is found to be

V_{0}

volt

when radiation of wavelength

λ_{0}

is used. If radiation of wavelength

{2 λ}_{0}

is used with the same metal then the stopping potential (in

volt

) will be

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

Light of wavelength

500 nm

is incident on a metal with work function

2.28 eV

. The de Broglie wavelength of the emitted electron is:

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

What is rest mass of photon?

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

When a metallic surface is illuminated with radiation of wavelength

λ

, the stopping potential is

V

. If the same surface is illuminated with radiation of wavelength

2 λ

, the stopping potential is

\frac{V}{4}

. The threshold wavelength for the metallic surface is:

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

In a photoelectric effect experiment, the graph of stopping potential $V$ versus reciprocal of wavelength obtained is shown in the figure. As the intensity of incident radiation is increased :

Question Image

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

A metal surface is illuminated by light of two different wavelengths 248 nm and 310 nm. The maximum speeds of the photoelectrons corresponding to these wavelengths are u₁ and u₂, respectively. If the ratio

u_{1} : u_{2} = 2 : 1

and

h c = 1240 eV nm

, the work function of the metal is nearly

HARD

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

Electrons are emitted with kinetic energy $T$ from a metal plate by an irradiation of light of intensity $J$ and frequency $v .$ Then, which of the following will be true?

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

In an experimental observation of the photoelectric effect, the stopping potential was plotted against the incident light frequency as shown in the figure below:

Question Image

If the work function of the metal is given by $ϕ_{0}$ , the angle $α$ is given by

(Here, $h$ and $e$ are Planck's constant and charge of electron respectively).

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

What is work function?

EASY

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

A photoelectric surface is illuminated successively by monochromatic light of wavelength

λ

and

\frac{λ}{2}

. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is:
(

h

= Planck's constant,

c

= speed of light)

HARD

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

In a historical experiment to determine Planck's constant, a metal surface was irradiated with light of different wavelengths. The emitted photoelectron energies were measured by applying a stopping potential. The relevant data for the wavelength

(λ)

of incident light and the corresponding stopping potential

(V_{0})

are given below:

$λ (μ m)$	$V_{0} (v o l t)$
0.3	2.0
0.4	1.0
0.5	0.4

Given that

c = 3 \times 10^{8} m s^{- 1} and e = 1.6 \times 10^{- 19} C,

Planck's constant (in units of

J s

) found from such an experiment is :

MEDIUM

Physics>Modern Physics>Dual Nature of Matter and Radiation>Photoelectric Effect

Following graphs show the variation of stopping potential corresponding to the frequency of incident radiation

(f)

for a given metal. The correct variation is shown in graph (

f_{0} =

Threshold frequency)

Question Image

Important Questions on Dual Nature of Matter and Radiation

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