(a) Write two main observations of the photoelectric effect experiment which could only be explained by Einstein's photoelectric equation. (b) Draw a graph showing the variation of photocurrent with the anode potential of a photocell.
(a) (i) A threshold frequencyν0 exists below which no photoemission occurs, whatever the intensity. (ii) The maximum kinetic energy of photoelectrons depends linearly on the frequency and is independent of intensity. (b) The photocurrent rises with anode potential and then saturates; on the negative side it falls to zero at the stopping potential −V0. For higher intensity (same frequency) the saturation current is larger with the same stopping potential (see figure).
Threshold frequency & Kmax∝ν;saturation curve with −V0
