Which of the following statements are correct ?
A. The saturation current is constant with collector plate potential for different frequencies of incident radiation.
B. The saturation current is different with collector plate potential for different frequencies of incident radiation.
C. The saturation current is different with collector plate potential for different intensity of incident radiation.
D. The saturation current is constant with collector plate potential for different intensity of incident radiation.
E. Below threshold frequency no photo electrons are emitted.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, C, E Only
The saturation current is fixed by the number of electrons emitted per second, which is proportional to the intensity of the light. The frequency decides the stopping potential, not the number of electrons.
(A) The saturation current is constant with collector plate potential for different frequencies of incident radiation. — Correct. For the same intensity and different frequencies (above threshold), the curves differ in stopping potential but reach the same saturation current.
(B) The saturation current is different with collector plate potential for different frequencies of incident radiation. — Incorrect. Frequency does not change the saturation current.
(C) The saturation current is different with collector plate potential for different intensity of incident radiation. — Correct. A higher intensity ejects more electrons per second, so the saturation current is larger.
(D) The saturation current is constant with collector plate potential for different intensity of incident radiation. — Incorrect. It changes with intensity, as in (C).
(E) Below threshold frequency no photo electrons are emitted. — Correct. Below the threshold frequency one photon does not have enough energy to overcome the work function, so no electron is emitted however intense the light is.
NCERT (2026-27):
Effect of Frequency of Incident Radiation on Stopping Potential – “… We obtain different values of stopping potential but the same value of the saturation current for incident radiation of different frequencies.”
Effect of Frequency of Incident Radiation on Stopping Potential – “… (ii) For a given photosensitive material and frequency of incident radiation, saturation current is found to be proportional to the intensity of incident radiation whereas the stopping potential is independent of its intensity (Fig. 11.3).”
Effect of Frequency of Incident Radiation on Stopping Potential – “… (iii) For a given photosensitive material, there exists a certain minimum cut-off frequency of the incident radiation, called the threshold frequency, below which no emission of photoelectrons takes place, no matter how intense the incident light is.”