Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 11 - Dual Nature of Radiation and Matter>Exercise>Q 25

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STATEMENT-1: The relative speed of separation between two photons travelling in opposite direction in vacuum is zero, where $c = 3 \times 10^{8} m s^{- 1}$ .

STATEMENT-2: Speed of a photon in vacuum does not depend on the frame of reference.

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Important Questions on Dual Nature of Radiation and Matter

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 11 - Dual Nature of Radiation and Matter>Exercise>Q 26

Light of wavelength

5000 Å

falls on a metal surface of work function

2.01 e V

. Find the kinetic energy of photoelectrons. Take:

h = 6 .62 \times 10^{- 34} Js, c = 3 \times 10^{8} m / s

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 11 - Dual Nature of Radiation and Matter>Exercise>Q 27

Calculate the kinetic energy of a photoelectron in

e V

emitted on shining light of wavelength

6.2 \times 10^{- 6} m

on a metal surface. The work function of the metal is

0.1 e V

.

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 11 - Dual Nature of Radiation and Matter>Exercise>Q 28

If the speed of photoelectrons is

10^{4} m s^{- 1}

, what should be the frequency of incident radiation on the potassium metal? Work function of potassium

= 2.3 e V

. Take, mass of electron,

m = 9 .1 \times 10^{- 31} kg

,

h = 6 .62 \times 10^{- 34} Js

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 11 - Dual Nature of Radiation and Matter>Exercise>Q 29

(I) The work function for the surface of aluminium is

4.2 e V

. How much potential difference will be required to stop the emission of maximum energy electrons emitted by the light of

2000 Å

wavelength?
(II) What will be the wavelength of that incident light for which stopping potential will be zero?
Given

h = 6.6 \times 10^{- 34} J s, c = 3 \times 10^{8} m s^{- 1}

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 11 - Dual Nature of Radiation and Matter>Exercise>Q 30

The work function, for a given photosensitive surface equals

2.5 e V

. When light of frequency,

ν

, falls on this surface, the emitted photoelectrons are completley stopped by applying a retarding potential of

4.1 V

. What is the value of

ν

?

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 11 - Dual Nature of Radiation and Matter>Exercise>Q 31

The linear momentum of an electron, initially at rest, accelerated through a potential difference of

100 V

is

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 11 - Dual Nature of Radiation and Matter>Exercise>Q 32

The material used for making thermionic cathode must have

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 11 - Dual Nature of Radiation and Matter>Exercise>Q 33

The time taken by a photoelectron to come out after the photon strikes is approximately