Question

A point source of light is used in a photoelectric effect. If the source is moved farther from the emitting metal, the stopping potential

• A. Will increase
• B. Will decrease
• C. Will remain constant
• D. Will either increase or decrease.

Answer 1

Answer: (C)

Will remain constant

The stopping potential (Vs) in photoelectric effect related with the incident light frequency $\left(\nu \right)$ by the following equation:
$e{V}_s=h\nu -\varphi$, where $\varphi$ is the work function of the material. It does not depend on the distance of the light source from the emitting metal. So the stopping potential will remain constant in the following case.

So, the answer is option (C).