The figure shows the variation of photocurrent with anode potential for four different radiations. Let \mathrm{I}_{\mathrm{a}}, \mathrm{I}_{\mathrm{b}}, \mathrm{I}_{\mathrm{c}} and \mathrm{I}_{\mathrm{d}} be the intensities for the curves a, b, c and d respectively \left[f_a, f_b, f_c\right. and f_d are frequencies respectively]