The Photoelectric current from a photosensitive metal, above the threshold frequency, depends on the:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → intensity of the incident radiation
The photoelectric current is the flow of photoelectrons emitted per second. Above the threshold frequency, each photon absorbed can free one electron, so the number of electrons emitted per second is proportional to the number of photons falling per second, that is, to the intensity of the radiation.
Option (1) frequency of the incident radiation — Incorrect. Above the threshold, the frequency decides the maximum kinetic energy of the photoelectrons, not how many are emitted; the saturation current is the same for different frequencies at the same intensity.
Option (2) work function of the metal — Incorrect. The work function sets the threshold frequency and the maximum kinetic energy; once emission takes place it does not set the current.
Option (3) intensity of the incident radiation — Correct. The photocurrent is directly proportional to the intensity of the incident radiation.
Option (4) stopping potential — Incorrect. The stopping potential is a result of the frequency (it measures the maximum kinetic energy); it is not a cause of the current.
NCERT (2026-27):
Effect of Intensity of Light on Photocurrent – “… It is found that the photocurrent increases linearly with intensity of incident light as shown graphically in Fig. 11.2. The photocurrent is directly proportional to the number of photoelectrons emitted per second.”