Keeping the frequency of the incident radiation and the accelerating potential fixed, the intensity of light is varied and the resulting photoelectric current is measured each time by the graph
Answer & explanation
Correct answer: option 3
The correct answer is Option (3)
At a fixed frequency (above the threshold) each photon can free one photoelectron, and the intensity of light is proportional to the number of photons arriving per second. With the accelerating potential fixed, the number of electrons collected per second, and hence the photoelectric current, is therefore directly proportional to the intensity.
\( I_{\mathrm{photo}} \propto \text{intensity} \)
The graph is a straight line through the origin, as in Option (3).
NCERT (2026-27):
Effect of Intensity of Light on Photocurrent – “… Keeping the frequency of the incident radiation and the potential fixed, the intensity of light is varied and the resulting photoelectric current is measured each time. It is found that the photocurrent increases linearly with intensity of incident light as shown graphically in Fig. 11.2.”
