question_answer

If the frequency of the incident radiation on the cathode of a photo-cell is doubled, how will the following change: (i) Kinetic energy of the electrons? (ii) Photoelectric current? (iii) Stopping potential? Justify your answer.           

Answer:

                (i) The K.E. of the photoelectron becomes more than double of its original energy. As the work function of the metal is fixed, so incident photon of higher energy will impart more energy to the photoelectron. (ii) The increase in frequency of incident radiation has no effect on photoelectric current. This is because of incident photon of increased energy cannot eject more than one electron from the metal surface. (iii) With the increase in frequency, the K.E. of the photoelectron increases, so stopping potential also increases.