Question

A point source causing photoelectric emission from a metallic plate is moved away from the plate. The variation of photoelectric current with distance from the source is correctly represented by the graph ______.
Fill in the blank with the correct answer from the options given below

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is B

A curve that decreases rapidly and then levels off. The photoelectric current depends on the intensity of light reaching the metallic surface. As the point source moves farther away from the plate, the intensity of light (and hence the photoelectric current) decreases. Since light intensity follows an inverse square law \((I \propto \frac{1}{r^2})\), the current initially decreases rapidly as the distance increases, but eventually it levels off at zero when the light is too weak to cause photoemission.