Q 12-11-002NEETNEET 2026Top questionEasy
A beam of light falls on a metal surface such that photo-electrons are generated. If power of the light source starts to decrease linearly with time $t$, then variation of the photocurrent $I$ and magnitude of the stopping potential $|V|$ with time is best represented by :
Answer: (A) see figure
Concept. Photocurrent $\propto$ photons per second (power); stopping potential depends only on frequency: $e|V| = h\nu - \phi$.
Step 1. Current. The power falls linearly, so $I$ falls linearly.
Step 2. Stopping potential. Frequency unchanged, so $|V|$ stays constant: graph (1).
Answer. Graph (1) (Option A).
Solution by Sreeraj P, M.Sc Physics