Sketch a graph between frequency of incident radiations and stopping potential for a given photosenstive material. What information can be obtained from the value of the intercept on the potential axis? A source of light of frequency greater than the threshold frequency is placed at a distance of 1m from the cathode of a photocell. The stopping potential is found to be V. If the distance of the light source from the cathode is reduced, explain giving reasons, what change will you observe in the (i) photoelectric current (i) stopping potential?

Explanation

For graph intercept on the potential axis=`-phi_0//e`. If the distance of the light source of the cathode is reduced, then (i) the photoelectric current is increases because the intensity of incident radiation increases. (ii) the stopping potential `V_0` remains the same because it is independent of the intensity of the incident radiations.