Question

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

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

Answer 1

The Correct Option is C

The stopping potential in the photoelectric effect is determined by the energy of the photons and the work function of the metal, not by the intensity or distance of the light source. According to the photoelectric effect, electrons are ejected when photons with energy greater than the work function hit the metal surface. The stopping potential \( V_s \) is given by the equation:

\( V_s = \frac{h\nu - \phi}{e} \)

where:

• \( h \) is Planck's constant.
• \( \nu \) is the frequency of the incident light.
• \( \phi \) is the work function of the metal.
• \( e \) is the charge of an electron.

The stopping potential depends only on the frequency of the incident light and is independent of the intensity or the distance of the light source from the metal surface. As such, removing the source farther from the emitting metal does not affect the frequency of the light, and thus, the stopping potential will remain constant. 
Therefore, the correct answer is: Will remain constant