Q. In the photoelectric effect, what is the effect of increasing the wavelength of incident light?
A.Increases the kinetic energy of emitted electrons
B.Decreases the kinetic energy of emitted electrons
C.Has no effect on the photoelectric effect
D.Increases the number of emitted electrons
Solution
Increasing the wavelength decreases the frequency of the light, which reduces the energy of the incident photons, thus decreasing the kinetic energy of emitted electrons.
Correct Answer: B — Decreases the kinetic energy of emitted electrons
Q. What happens to the number of emitted electrons if the intensity of light is increased while keeping the frequency above the threshold?
A.The number of emitted electrons decreases
B.The number of emitted electrons increases
C.The energy of each emitted electron increases
D.No electrons are emitted
Solution
Increasing the intensity of light increases the number of photons incident on the surface, leading to more emitted electrons, provided the frequency is above the threshold.
Correct Answer: B — The number of emitted electrons increases
Q. What happens to the number of emitted electrons if the intensity of the light is increased while keeping the frequency above the threshold?
A.The number of emitted electrons decreases
B.The number of emitted electrons increases
C.The energy of each emitted electron increases
D.No effect on the number of emitted electrons
Solution
Increasing the intensity of light increases the number of photons, which in turn increases the number of emitted electrons, provided the frequency is above the threshold.
Correct Answer: B — The number of emitted electrons increases
Q. What is the effect of increasing the wavelength of incident light on the photoelectric effect?
A.More electrons are emitted
B.Fewer electrons are emitted
C.The kinetic energy of emitted electrons increases
D.The work function decreases
Solution
Increasing the wavelength decreases the frequency of the incident light, which can lead to fewer or no electrons being emitted if the frequency falls below the threshold frequency.
Q. What is the effect of increasing the work function of a metal on the photoelectric effect?
A.More electrons are emitted
B.Fewer electrons are emitted
C.The frequency of light must be increased
D.Both B and C are correct
Solution
Increasing the work function means that a higher frequency of light is required to emit electrons, resulting in fewer electrons being emitted for a given frequency of light.
Q. What is the minimum frequency of light required to eject electrons from a metal surface in the photoelectric effect?
A.It depends on the intensity of light
B.It is constant for all metals
C.It depends on the work function of the metal
D.It is equal to the energy of the incident photons
Solution
The minimum frequency required to eject electrons is determined by the work function of the metal, given by the equation E = hf, where E is the work function, h is Planck's constant, and f is the frequency.
Correct Answer: C — It depends on the work function of the metal
Q. What is the relationship between the stopping potential and the maximum kinetic energy of emitted electrons in the photoelectric effect?
A.Stopping potential is directly proportional to the work function
B.Stopping potential is directly proportional to the maximum kinetic energy
C.Stopping potential is inversely proportional to the frequency
D.Stopping potential has no relation to kinetic energy
Solution
The stopping potential (V) is directly proportional to the maximum kinetic energy (KE) of the emitted electrons, given by the equation KE = eV, where e is the charge of the electron.
Correct Answer: B — Stopping potential is directly proportional to the maximum kinetic energy
Q. What is the relationship between the stopping potential and the maximum kinetic energy of the emitted electrons in the photoelectric effect?
A.Stopping potential is directly proportional to the work function
B.Stopping potential is inversely proportional to the maximum kinetic energy
C.Stopping potential is equal to the maximum kinetic energy
D.Stopping potential has no relation to the photoelectric effect
Solution
The stopping potential (V) is related to the maximum kinetic energy (KE) of the emitted electrons by the equation KE = eV, where e is the charge of the electron.
Correct Answer: C — Stopping potential is equal to the maximum kinetic energy