Which of the following statements are correct?
A. The number of photoelectrons emitted per second is directly proportional to the intensity of incident radiation.
B. The minimum value of photoelectric current is called saturation current.
C. For a given frequency, stopping potential is independent of its intensity.
D. The stopping potential is same for all frequencies.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A and C only
The photoelectric current measures the number of photoelectrons reaching the collector per second, while the stopping potential measures the maximum kinetic energy of the fastest photoelectrons, \( eV_0 = h\nu-\phi_0 \).
(A) The number of photoelectrons emitted per second is directly proportional to the intensity of incident radiation. — Correct. More intense light of a given frequency (above the threshold) delivers more photons per second, and each photon ejects at most one electron.
(B) The minimum value of photoelectric current is called saturation current. — Incorrect. The saturation current is the maximum value of the photoelectric current, reached when all the emitted electrons reach the collector.
(C) For a given frequency, stopping potential is independent of its intensity. — Correct. From \( eV_0 = h\nu-\phi_0 \), the stopping potential depends only on the frequency and the metal, not on the intensity.
(D) The stopping potential is same for all frequencies. — Incorrect. \( V_0 \) increases linearly with the frequency \( \nu \).
NCERT (2026-27):
Effect of Frequency of Incident Radiation on Stopping Potential – “… (i) For a given photosensitive material and frequency of incident radiation (above the threshold frequency), the photoelectric current is directly proportional to the intensity of incident light (Fig. 11.2). (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). … Above the threshold frequency, the stopping potential or equivalently the maximum kinetic energy of the emitted photoelectrons increases linearly with the frequency of the incident radiation, but is independent of its intensity (Fig. 11.5).”