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

Electron emission from a metal surface, known as the photoelectric effect, is triggered by incident light. The resulting photoelectric current, representing the electron flow rate, is contingent upon the incident light's intensity. Light intensity diminishes with distance from the source following an inverse square law. Consequently, as the distance from a point light source increases, the light intensity and the photoelectric current decrease proportionally to the square of this distance.

This relationship is mathematically defined as:

$I \propto \frac{1}{d^2}$

where $I$ denotes light intensity and $d$ represents the distance from the light source. Thus, the photoelectric current is inversely proportional to the square of the distance.

A graph depicting this relationship would illustrate the photoelectric current decreasing as the distance increases, aligning with "Graph (II)".