Final answer:
In the photoelectric effect, the stopping potential remains constant when the distance between the light source and the metal surface is increased, because the potential is determined by the energy of the photons, which is not affected by the distance.
Therefore, the correct answer is: option (c) will remain constant
Step-by-step explanation:
The question relates to the photoelectric effect, which describes the emission of electrons from a metal when light shines upon it. Specifically, about the change in the stopping potential when the distance between a point source of light and the metal surface is increased.
According to the principles of the photoelectric effect, the stopping potential is determined by the energy of the photons, not their intensity.
Therefore, moving the light source further away will decrease the intensity of the light (number of photons reaching the surface) but will not change the energy of individual photons as long as the frequency of the light remains constant. Hence, the stopping potential will remain constant (c) as the distance increases.