Question

Sketch the graphs showing variation of stopping potential with frequency of incident radiations for two photosensitive materials A and B having threshold frequencies $$V_A>V_B$$
(i) In which case is the stopping potential more and why?
(ii) Does the slope of the graph depend on the nature of the material used? Explain

Answer 1

(i) From the graph for the same value of 'v', stopping potential is more for material 'B'
From Einstein's photoelectric equation
$$eV_0=hv-hv_0$$

$$V_0 =\dfrac{h}{e}-\dfrac{h}{e}_0=\dfrac{h}{e}(v-v_0)$$

Therefore$$ V_0$$ is higher for lower value of $$V_0$$

ii. No, as slope is given by $$\dfrac{h}{e}$$ which is a universal constant.