Question 1

In a photoelectric experiment, the stopping potential is measured to be 1.5 V for a certain frequency of incident light. If the frequency of the incident light is doubled, what will be the new stopping potential, assuming the work function remains constant?

Accepted Answer

Correct Option: C. Solution: Doubling the frequency of the incident light increases the energy of the photons, which increases the maximum kinetic energy of the emitted photoelectrons. As a result, the stopping potential will be greater than 3.0 V.

Question 2

In a photoelectric experiment, the stopping potential is found to be 3 V for light of frequency $8 	imes 10^{14}$ Hz. What will be the stopping potential if the frequency of the incident light is increased to $1.2 	imes 10^{15}$ Hz, assuming the work function of the metal remains unchanged?

Accepted Answer

Correct Option: B. Solution: The stopping potential is directly proportional to the frequency of the incident light. If the frequency increases by a factor of 1.5, the stopping potential also increases by the same factor: $3 	imes 1.5 = 4.5$ V.

Question 3

In a photoelectric experiment, the stopping potential $V_0$ is found to be independent of which of the following parameters?

Accepted Answer

Correct Option: A. Solution: The stopping potential $V_0$ is independent of the intensity of the incident light. It depends on the frequency of the incident light and the work function of the metal.

Question 4

Which of the following factors does NOT affect the stopping potential in a photoelectric effect experiment?

Accepted Answer

Correct Option: B. Solution: The stopping potential is independent of the intensity of incident light but depends on the frequency of the light and the nature of the emitter material.

Question 5

Which type of electron emission occurs when electrons are emitted from a metal surface due to the application of a strong electric field?

Accepted Answer

Correct Option: B. Solution: Field emission occurs when a strong electric field is applied to a metal, pulling electrons out of the metal surface.

Question 6

Which observation by Hallwachs and Lenard demonstrated the existence of a threshold frequency in the photoelectric effect?

Accepted Answer

Correct Option: B. Solution: Hallwachs and Lenard observed that no electrons were emitted when the frequency of the incident light was below a certain value, known as the threshold frequency.

Question 7

Which of the following statements is true regarding the stopping potential in the photoelectric effect?

Accepted Answer

Correct Option: C. Solution: The stopping potential $V_0$ is directly related to the maximum kinetic energy of the emitted electrons, as given by $eV_0 = K_{	ext{max}}$.

Question 8

If the work function of a metal is $2.0 \ eV$ and it is illuminated with light of frequency $8 	imes 10^{14} \ Hz$, what is the stopping potential required to stop the photoelectrons?

Accepted Answer

Correct Option: A. Solution: The energy of the incident photons is $E = h
u = 6.63 	imes 10^{-34} 	imes 8 	imes 10^{14} = 5.304 	imes 10^{-19} \ J = 3.31 \ eV$. The maximum kinetic energy of the photoelectrons is $K_{max} = E - \phi_0 = 3.31 - 2.0 = 1.31 \ eV$. Therefore, the stopping potential $V_0 = \frac{K_{max}}{e} = 1.31 \ V$.

Question 9

Which of the following statements about the photoelectric effect is true?

Accepted Answer

Correct Option: B. Solution: The stopping potential is determined by the frequency of the incident light and is independent of its intensity.

Question 10

According to the de Broglie hypothesis, what is the wavelength of an electron moving with a momentum of $3.3 	imes 10^{-24}$ kg m/s?

Accepted Answer

Correct Option: A. Solution: The de Broglie wavelength $\lambda$ is given by $\lambda = \frac{h}{p}$, where $h$ is Planck's constant ($6.63 	imes 10^{-34}$ Js) and $p$ is the momentum. Substituting the values, $\lambda = \frac{6.63 	imes 10^{-34}}{3.3 	imes 10^{-24}} = 2.0 	imes 10^{-10}$ m.

Question 11

According to Einstein's photoelectric equation, what happens to the maximum kinetic energy of photoelectrons when the frequency of the incident light increases?

Accepted Answer

Correct Option: C. Solution: According to Einstein's photoelectric equation, the maximum kinetic energy of photoelectrons increases linearly with the frequency of the incident light.

Question 12

For a given metal, if the frequency of incident light is increased beyond the threshold frequency, which of the following statements is true regarding the stopping potential?

Accepted Answer

Correct Option: A. Solution: The stopping potential increases linearly with the frequency of incident radiation for a given photosensitive material, as greater frequency results in greater maximum kinetic energy of the photoelectrons.

Question 13

According to the classical wave theory, what should happen to the maximum kinetic energy of photoelectrons as the intensity of incident light increases?

Accepted Answer

Correct Option: A. Solution: Classical wave theory predicts that the maximum kinetic energy of photoelectrons should increase with the intensity of incident light, which contradicts experimental observations.

Question 14

Which type of electron emission occurs when a metal surface is illuminated by light of suitable frequency?

Accepted Answer

Correct Option: C. Solution: Photoelectric emission occurs when light of suitable frequency illuminates a metal surface, causing electrons to be emitted.

Question 15

If the stopping potential for electrons emitted from a metal surface is $1.5 	ext{ V}$ when light of frequency $8 	imes 10^{14} 	ext{ Hz}$ is used, what is the work function of the metal?

Accepted Answer

Correct Option: B. Solution: The energy of the incident photons is $E = h 
u = (6.63 	imes 10^{-34} 	ext{ Js})(8 	imes 10^{14} 	ext{ Hz}) = 5.304 	imes 10^{-19} 	ext{ J} = 3.31 	ext{ eV}$. The stopping potential $V_0$ is $1.5 	ext{ V}$, so the maximum kinetic energy is $1.5 	ext{ eV}$. Therefore, the work function $\Phi_0 = E - eV_0 = 3.31 	ext{ eV} - 1.5 	ext{ eV} = 1.81 	ext{ eV}$.

Question 16

A metal surface is illuminated with light of frequency $8 	imes 10^{14}$ Hz, resulting in the emission of photoelectrons with maximum kinetic energy of $2.5 	imes 10^{-19}$ J. If the work function of the metal is $3.2 	imes 10^{-19}$ J, what is the value of Planck's constant $h$?

Accepted Answer

Correct Option: A. Solution: Using Einstein's photoelectric equation $E_k = h
u - \Phi$, where $E_k$ is the kinetic energy, $
u$ is the frequency, and $\Phi$ is the work function. Rearranging, $h = \frac{E_k + \Phi}{
u}$. Substituting the given values, $h = \frac{2.5 	imes 10^{-19} 	ext{ J} + 3.2 	imes 10^{-19} 	ext{ J}}{8 	imes 10^{14} 	ext{ Hz}} = 6.63 	imes 10^{-34}$ J\cdot s.

Question 17

According to Einstein's photoelectric equation, which of the following statements is correct regarding the photoelectric effect?

Accepted Answer

Correct Option: C. Solution: According to Einstein's photoelectric equation, the maximum kinetic energy of photoelectrons is determined by the frequency of the incident light and is independent of its intensity.

Question 18

In the context of wave-particle duality, which experiment provides evidence for the wave nature of electrons?

Accepted Answer

Correct Option: B. Solution: The double-slit experiment provides evidence for the wave nature of electrons as it shows interference patterns, which are characteristic of wave-like behavior.

Question 19

In an experiment on the photoelectric effect, it is observed that the photocurrent increases linearly with the intensity of incident light. Which of the following best explains this observation?

Accepted Answer

Correct Option: B. Solution: The photocurrent is directly proportional to the number of photoelectrons emitted per second, which increases with the number of photons striking the surface per unit time. This is why the photocurrent increases linearly with the intensity of incident light.

Question 20

Which of the following statements correctly describes the concept of work function in the context of electron emission from metals?

Accepted Answer

Correct Option: B. Solution: The work function is defined as the minimum energy needed for an electron to escape from the metal surface, overcoming the attractive forces of the ions.

Question 21

In the context of the photoelectric effect, what is the effect of increasing the intensity of light on the maximum kinetic energy of emitted photoelectrons?

Accepted Answer

Correct Option: C. Solution: The maximum kinetic energy of emitted photoelectrons is independent of the intensity of light; it depends on the frequency of the incident light.

Question 22

Which of the following statements about photons is true?

Accepted Answer

Correct Option: B. Solution: Photon energy is independent of light intensity; it depends only on the frequency of the light.

Question 23

Which of the following experiments confirmed the wave nature of light as predicted by Maxwell's equations?

Accepted Answer

Correct Option: C. Solution: Hertz's experiments on electromagnetic waves confirmed the wave nature of light as predicted by Maxwell's equations.

Question 24

Consider a scenario where a monochromatic light of frequency $8 	imes 10^{14}$ Hz is incident on a metal surface with a work function of $2.5$ eV. If the stopping potential measured is $1.5$ V, which of the following statements is true about the photoelectric effect observed?

Accepted Answer

Correct Option: D. Solution: The photoelectric current increases with the intensity of incident light, as more photons result in more emitted electrons. The stopping potential depends on the frequency of the incident light, and the maximum kinetic energy of the emitted electrons can be calculated using the equation $K_{	ext{max}} = eV_0 = h
u - \Phi_0$, which is not $1.5$ eV in this scenario.

Question 25

In an experiment, light of frequency $8 	imes 10^{14}$ Hz is incident on a metal surface with a work function of $2.5$ eV. What is the stopping potential required to bring the photocurrent to zero?

Accepted Answer

Correct Option: B. Solution: The energy of the incident photons is $E = h 
u = (6.63 	imes 10^{-34} 	ext{ Js})(8 	imes 10^{14} 	ext{ Hz}) = 5.304 	imes 10^{-19}$ J, which is equivalent to $3.31$ eV. The stopping potential $V_0$ is given by $eV_0 = E - \Phi_0$, where $\Phi_0 = 2.5$ eV. Thus, $V_0 = 3.31 - 2.5 = 0.81$ eV, approximately $2.0$ V.

Question 26

According to Einstein's photoelectric equation, what is the relationship between the stopping potential $V_0$ and the frequency $v$ of the incident light?

Accepted Answer

Correct Option: A. Solution: Einstein's photoelectric equation shows that the stopping potential $V_0$ is directly proportional to the frequency $v$ of the incident light.

Question 27

Consider a photon with frequency $
u = 5 	imes 10^{14}$ Hz. If Planck's constant $h$ is $6.63 	imes 10^{-34}$ J\cdot s, what is the energy of this photon?

Accepted Answer

Correct Option: A. Solution: The energy of a photon is given by $E = h
u$. Substituting the given values, $E = (6.63 	imes 10^{-34} 	ext{ J\cdot s}) 	imes (5 	imes 10^{14} 	ext{ Hz}) = 3.32 	imes 10^{-19}$ J.

Question 28

Which phenomenon demonstrates the wave nature of light?

Accepted Answer

Correct Option: C. Solution: Interference is a phenomenon that demonstrates the wave nature of light, as it involves the superposition of light waves.

Question 29

Which component in the photoelectric-effect experimental setup is responsible for measuring the flow of electrons?

Accepted Answer

Correct Option: B. Solution: The microammeter measures the photoelectric current, which is the flow of electrons emitted from the photosensitive plate.

Question 30

In the context of the photoelectric effect, why does the classical wave theory fail to explain the independence of maximum kinetic energy from light intensity?

Accepted Answer

Correct Option: A. Solution: Classical wave theory assumes that energy is absorbed continuously, which implies that higher intensity should increase the energy absorbed by electrons, thus increasing their kinetic energy. This contradicts the observed independence of kinetic energy from intensity.

Question 31

What is the energy of a photon with frequency $
u$?

Accepted Answer

Correct Option: A. Solution: The energy of a photon is given by the equation $E = h 
u$, where $h$ is Planck's constant and $
u$ is the frequency.

Question 32

In the photoelectric effect, what happens when the frequency of incident light is below the threshold frequency?

Accepted Answer

Correct Option: B. Solution: When the frequency of the incident light is below the threshold frequency, no photoelectric emission occurs, regardless of the light's intensity.

Question 33

In the context of the photoelectric effect, if the intensity of incident light is increased while keeping the frequency constant, which of the following outcomes is expected?

Accepted Answer

Correct Option: B. Solution: Increasing the intensity of light increases the number of photons incident per second, thus increasing the number of emitted electrons per second, but it does not affect the maximum kinetic energy of the electrons.

Question 34

What is the threshold frequency for a metal if its work function is 3.0 eV?

Accepted Answer

Correct Option: B. Solution: The threshold frequency $v_0$ is given by $v_0 = \frac{\Phi_0}{h}$, where $\Phi_0 = 3.0 	ext{ eV} = 3.0 	imes 1.602 	imes 10^{-19} 	ext{ J}$ and $h = 6.626 	imes 10^{-34} 	ext{ J s}$. Thus, $v_0 = \frac{3.0 	imes 1.602 	imes 10^{-19}}{6.626 	imes 10^{-34}} = 6.25 	imes 10^{14} 	ext{ Hz}$.

Question 35

For an electron moving with a speed of $5.4 	imes 10^6 	ext{ m/s}$, what is the de Broglie wavelength associated with it?

Accepted Answer

Correct Option: A. Solution: The de Broglie wavelength $\lambda$ is given by $\lambda = \frac{h}{mv}$. Substituting the given values: $h = 6.63 	imes 10^{-34} 	ext{ Js}$, $m = 9.11 	imes 10^{-31} 	ext{ kg}$, and $v = 5.4 	imes 10^6 	ext{ m/s}$, we get $\lambda = \frac{6.63 	imes 10^{-34}}{9.11 	imes 10^{-31} 	imes 5.4 	imes 10^6} = 0.135 	ext{ nm}$.

Question 36

In an experiment on the photoelectric effect, the stopping potential for a certain metal is found to be 2 V when illuminated with light of frequency $8 	imes 10^{14}$ Hz. If the frequency of the incident light is doubled, what happens to the stopping potential?

Accepted Answer

Correct Option: C. Solution: The stopping potential is directly related to the frequency of the incident light. Doubling the frequency increases the stopping potential.

Question 37

According to Einstein's photoelectric equation, what is the relationship between the maximum kinetic energy of the emitted photoelectrons and the frequency of incident light?

Accepted Answer

Correct Option: A. Solution: According to Einstein's photoelectric equation, the maximum kinetic energy $K_{	ext{max}} = h
u - \phi_0$ depends linearly on the frequency $
u$ of the incident light.

Question 38

A proton and an electron are moving with the same de Broglie wavelength. Which of the following statements is correct?

Accepted Answer

Correct Option: B. Solution: For particles with the same de Broglie wavelength $\lambda$, $\lambda = \frac{h}{p}$ implies $p = \frac{h}{\lambda}$. Since the proton is much heavier than the electron, for the same momentum, the electron must have a higher speed to compensate for its lower mass.

Question 39

In a photoelectric experiment, the stopping potential is plotted against the frequency of incident light. What is the slope of this graph?

Accepted Answer

Correct Option: A. Solution: The slope of the stopping potential vs frequency graph is given by $h/e$, where $h$ is Planck's constant and $e$ is the charge of an electron.

Question 40

In the context of electron emission, what is the minimum energy required for an electron to escape from the metal surface called?

Accepted Answer

Correct Option: B. Solution: The minimum energy required for an electron to escape from the metal surface is known as the work function, denoted by $\Phi_0$.

Question 41

Which of the following best describes the relationship between the stopping potential and the frequency of incident light in the photoelectric effect?

Accepted Answer

Correct Option: C. Solution: The stopping potential is directly proportional to the frequency of the incident light, as described by the equation $eV_0 = h
u - \Phi_0$, where $V_0$ is the stopping potential, $
u$ is the frequency, and $\Phi_0$ is the work function.

Question 42

Which of the following phenomena could not be explained by the classical wave theory of light?

Accepted Answer

Correct Option: C. Solution: The classical wave theory could not explain the photoelectric effect, particularly the threshold frequency, instantaneous emission, and independence of maximum kinetic energy from intensity.

Question 43

In the context of the photoelectric effect, what is the significance of the threshold frequency?

Accepted Answer

Correct Option: A. Solution: The threshold frequency is the minimum frequency of incident light required to cause photoelectric emission from a material, independent of light intensity.

Question 44

Which of the following statements correctly describes the effect of increasing the frequency of incident light on the photoelectric emission from a metal surface?

Accepted Answer

Correct Option: B. Solution: Increasing the frequency of the incident light increases the maximum kinetic energy of the emitted electrons, as described by Einstein's photoelectric equation.

Question 45

What happens to the photocurrent when a retarding potential is applied in a photoelectric experiment?

Accepted Answer

Correct Option: C. Solution: With retarding potential, the photocurrent decreases and eventually reaches zero at the stopping potential.

Question 46

A metal surface is irradiated with light of frequency $
u$ which is above the threshold frequency $
u_0$. If the intensity of the light is increased, what happens to the stopping potential?

Accepted Answer

Correct Option: C. Solution: The stopping potential is independent of the intensity of the incident light and depends only on the frequency of the light and the work function of the metal.

Question 47

In a photoelectric effect experiment, what is the effect of applying a retarding potential on the photocurrent?

Accepted Answer

Correct Option: B. Solution: With retarding potential, photocurrent decreases to zero at stopping potential.

Question 48

Consider a metal with a work function of $2.5 	ext{ eV}$. If light of frequency $7 	imes 10^{14} 	ext{ Hz}$ is incident on the metal, what is the maximum kinetic energy of the emitted photoelectrons?

Accepted Answer

Correct Option: A. Solution: The energy of the incident photons is given by $E = h 
u = (6.63 	imes 10^{-34} 	ext{ Js})(7 	imes 10^{14} 	ext{ Hz}) = 4.641 	imes 10^{-19} 	ext{ J} = 2.9 	ext{ eV}$. The maximum kinetic energy is $E - \Phi_0 = 2.9 	ext{ eV} - 2.5 	ext{ eV} = 0.4 	ext{ eV}$.

Question 49

In the context of the photon picture of radiation, which of the following statements is true about the energy of a photon?

Accepted Answer

Correct Option: B. Solution: The energy of a photon is given by $E = h
u$, where $h$ is Planck's constant and $
u$ is the frequency of light. This energy is independent of the light's intensity, which only affects the number of photons.

Question 50

J.J. Thomson's experiment to determine the specific charge (e/m) of cathode ray particles involved the use of which of the following setups?

Accepted Answer

Correct Option: C. Solution: J.J. Thomson used a discharge tube with mutually perpendicular electric and magnetic fields to determine the specific charge (e/m) of cathode ray particles, proving their universality and identifying them as electrons.

Question 51

What is the relationship between the energy of a photon and its frequency?

Accepted Answer

Correct Option: A. Solution: The energy of a photon is given by $E = h
u$, where $h$ is Planck's constant and $
u$ is the frequency. Thus, energy is directly proportional to the frequency.

Question 52

According to Einstein's photoelectric equation, what is the relationship between the maximum kinetic energy of photoelectrons and the frequency of incident light?

Accepted Answer

Correct Option: C. Solution: According to Einstein's photoelectric equation, the maximum kinetic energy of photoelectrons is given by $K_{	ext{max}} = h
u - \Phi_0$, where $h$ is Planck's constant, $
u$ is the frequency of the incident light, and $\Phi_0$ is the work function of the metal.

Question 53

A metal has a threshold frequency of $4 	imes 10^{14}$ Hz. If the incident light has a frequency of $6 	imes 10^{14}$ Hz, what is the effect on the photoelectric emission?

Accepted Answer

Correct Option: A. Solution: Since the incident frequency is greater than the threshold frequency, photoelectric emission occurs with electrons having maximum kinetic energy, which is proportional to the difference between the incident and threshold frequencies.

Question 54

A metal surface has a threshold frequency of $5 	imes 10^{14} 	ext{ Hz}$. If light of frequency $6 	imes 10^{14} 	ext{ Hz}$ is shone on it, what is the stopping potential required to halt the photoelectrons?

Accepted Answer

Correct Option: B. Solution: The energy of the incident photons is $E = h 
u = (6.63 	imes 10^{-34} 	ext{ Js})(6 	imes 10^{14} 	ext{ Hz}) = 3.978 	imes 10^{-19} 	ext{ J} = 2.48 	ext{ eV}$. The work function is $\Phi_0 = h 
u_0 = (6.63 	imes 10^{-34} 	ext{ Js})(5 	imes 10^{14} 	ext{ Hz}) = 3.315 	imes 10^{-19} 	ext{ J} = 2.07 	ext{ eV}$. The stopping potential $V_0$ is given by $eV_0 = E - \Phi_0 = 2.48 	ext{ eV} - 2.07 	ext{ eV} = 0.41 	ext{ eV}$, hence $V_0 = 0.41 	ext{ V}$.

Question 55

What is the minimum energy required by an electron to escape from a metal surface called?

Accepted Answer

Correct Option: C. Solution: The minimum energy required by an electron to escape from a metal surface is called the work function.

Question 56

What happens to the photocurrent when the positive collector potential is increased until it saturates?

Accepted Answer

Correct Option: B. Solution: As positive collector potential increases, photocurrent increases and then saturates when all emitted photoelectrons are collected.

Question 57

In an experimental setup for the photoelectric effect, what is the role of the photosensitive emitter plate?

Accepted Answer

Correct Option: A. Solution: The photosensitive emitter plate emits electrons when it is illuminated by light of suitable frequency, which is a fundamental aspect of the photoelectric effect.

Question 58

Which of the following metals would most likely exhibit photoelectric emission when exposed to visible light?

Accepted Answer

Correct Option: C. Solution: Alkali metals like cesium are sensitive to visible light and can exhibit photoelectric emission.

Question 59

Which of the following processes can supply the minimum energy required for electron emission from a metal surface?

Accepted Answer

Correct Option: D. Solution: The minimum energy required for electron emission from a metal surface can be supplied by thermionic emission, field emission, or photoelectric emission.

Question 60

In a photoelectric experiment, the stopping potential is found to be 1.5 V when light of frequency $8 	imes 10^{14}$ Hz is used. What is the work function of the metal used in the experiment? (Planck's constant $h = 6.63 	imes 10^{-34}$ Js, charge of electron $e = 1.602 	imes 10^{-19}$ C)

Accepted Answer

Correct Option: A. Solution: The maximum kinetic energy of the photoelectrons is given by $K_{	ext{max}} = eV_0 = 1.602 	imes 10^{-19} 	imes 1.5 = 2.403 	imes 10^{-19}$ J. The energy of the incident photon is $E = h 
u = 6.63 	imes 10^{-34} 	imes 8 	imes 10^{14} = 5.304 	imes 10^{-19}$ J. The work function $\Phi_0 = E - K_{	ext{max}} = 5.304 	imes 10^{-19} - 2.403 	imes 10^{-19} = 2.901 	imes 10^{-19}$ J, which is approximately 1.32 eV.

Question 61

In an experiment, light of frequency $6 	imes 10^{14} \ Hz$ is incident on a metal with a work function of $2.5 \ eV$. What is the maximum kinetic energy of the emitted electrons?

Accepted Answer

Correct Option: C. Solution: The energy of the photons is $E = h
u = 6.63 	imes 10^{-34} 	imes 6 	imes 10^{14} = 3.978 	imes 10^{-19} \ J = 2.48 \ eV$. The maximum kinetic energy is $K_{max} = E - \phi_0 = 2.48 - 2.5 = -0.02 \ eV$. Since the kinetic energy cannot be negative, the correct interpretation is that the maximum kinetic energy of the emitted electrons is $0.0 \ eV$ and no electrons are emitted. However, if the work function is less than the photon energy, $K_{max} = 0.5 \ eV$.

Question 62

If the frequency of incident light is increased while keeping its intensity constant, what effect does it have on the stopping potential in the photoelectric effect?

Accepted Answer

Correct Option: C. Solution: The stopping potential increases with the frequency of the incident light, as the maximum kinetic energy of the photoelectrons increases with frequency.

Question 63

What happens to the photoelectric current when the intensity of incident light is increased while keeping the frequency constant?

Accepted Answer

Correct Option: C. Solution: The photoelectric current increases with the intensity of incident light because more photons are available to release more electrons.

Question 64

Which of the following observations cannot be explained by the classical wave theory of light?

Accepted Answer

Correct Option: D. Solution: The classical wave theory predicts that energy is absorbed continuously, which should make the maximum kinetic energy of photoelectrons dependent on the intensity of light. However, the photoelectric effect shows that the maximum kinetic energy is independent of intensity, which cannot be explained by wave theory.

Physical Quantity	Symbol	Dimensions	Unit	Remarks
Planck's constant	h	[ML²T⁻¹]	Js	E = hv
Stopping potential	V₀	[ML²T⁻³A⁻¹]	V	eVo - Kmax
Work function	Ф₀	[ML²T⁻²]	J; eV	Kₘₐₓ = E - Ф₀
Threshold frequency	V₀	[T⁻¹]	Hz	v = /h
de Broglie wavelength	A	[L]	m	A = h/p

Dual Nature of Radiation ..

Learning Objectives

Revision Notes & Summary

Chapter 11: Dual Nature of Radiation and Matter

11.1 Introduction

11.2 Key Concepts

Physical Quantities

11.3 Points to Ponder

11.4 Experimental Study of Photoelectric Effect

11.5 Observations on Photoelectric Effect

11.6 Examples

11.7 Exercises

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Tips for Success

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Multiple Choice Questions

Q1.In a photoelectric experiment, the stopping potential is measured to be 1.5 V for a certain frequency of incident light. If the frequency of the incident light is doubled, what will be the new stopping potential, assuming the work function remains constant?

Correct Answer: C

Correct Answer: B

Q3.In a photoelectric experiment, the stopping potential V0V_0V0​ is found to be independent of which of the following parameters?

Correct Answer: A

Q4.Which of the following factors does NOT affect the stopping potential in a photoelectric effect experiment?

Correct Answer: B

Q5.Which type of electron emission occurs when electrons are emitted from a metal surface due to the application of a strong electric field?

Correct Answer: B

Q6.Which observation by Hallwachs and Lenard demonstrated the existence of a threshold frequency in the photoelectric effect?

Correct Answer: B

Q7.Which of the following statements is true regarding the stopping potential in the photoelectric effect?

Correct Answer: C

Q8.If the work function of a metal is 2.0 eV2.0 \ eV2.0 eV and it is illuminated with light of frequency 8×1014 Hz8 \times 10^{14} \ Hz8×1014 Hz, what is the stopping potential required to stop the photoelectrons?

Correct Answer: A

Q9.Which of the following statements about the photoelectric effect is true?

Correct Answer: B

Q10.According to the de Broglie hypothesis, what is the wavelength of an electron moving with a momentum of 3.3×10−243.3 \times 10^{-24}3.3×10−24 kg m/s?

Correct Answer: A

Q11.According to Einstein's photoelectric equation, what happens to the maximum kinetic energy of photoelectrons when the frequency of the incident light increases?

Correct Answer: C

Q12.For a given metal, if the frequency of incident light is increased beyond the threshold frequency, which of the following statements is true regarding the stopping potential?

Correct Answer: A

Q13.According to the classical wave theory, what should happen to the maximum kinetic energy of photoelectrons as the intensity of incident light increases?

Correct Answer: A

Q14.Which type of electron emission occurs when a metal surface is illuminated by light of suitable frequency?

Correct Answer: C

Q15.If the stopping potential for electrons emitted from a metal surface is 1.5 V1.5 \text{ V}1.5 V when light of frequency 8×1014 Hz8 \times 10^{14} \text{ Hz}8×1014 Hz is used, what is the work function of the metal?

Correct Answer: B

Correct Answer: A

Q17.According to Einstein's photoelectric equation, which of the following statements is correct regarding the photoelectric effect?

Correct Answer: C

Q18.In the context of wave-particle duality, which experiment provides evidence for the wave nature of electrons?

Correct Answer: B

Q19.In an experiment on the photoelectric effect, it is observed that the photocurrent increases linearly with the intensity of incident light. Which of the following best explains this observation?

Correct Answer: B

Q20.Which of the following statements correctly describes the concept of work function in the context of electron emission from metals?

Correct Answer: B

Q21.In the context of the photoelectric effect, what is the effect of increasing the intensity of light on the maximum kinetic energy of emitted photoelectrons?

Correct Answer: C

Q22.Which of the following statements about photons is true?

Correct Answer: B

Q23.Which of the following experiments confirmed the wave nature of light as predicted by Maxwell's equations?

Correct Answer: C

Correct Answer: D

Q25.In an experiment, light of frequency 8×10148 \times 10^{14}8×1014 Hz is incident on a metal surface with a work function of 2.52.52.5 eV. What is the stopping potential required to bring the photocurrent to zero?

Correct Answer: B

Q26.According to Einstein's photoelectric equation, what is the relationship between the stopping potential V0V_0V0​ and the frequency vvv of the incident light?

Correct Answer: A

Q27.Consider a photon with frequency ν=5×1014\nu = 5 \times 10^{14}ν=5×1014 Hz. If Planck's constant hhh is 6.63×10−346.63 \times 10^{-34}6.63×10−34 J\cdot s, what is the energy of this photon?

Correct Answer: A

Q28.Which phenomenon demonstrates the wave nature of light?

Correct Answer: C

Q29.Which component in the photoelectric-effect experimental setup is responsible for measuring the flow of electrons?

Correct Answer: B

Q30.In the context of the photoelectric effect, why does the classical wave theory fail to explain the independence of maximum kinetic energy from light intensity?