The figure shows the variation of photo-current (i) and anode potential (V) for a photo sensitive surface for three different radiations. Let I_a, I_b and I_c be the intensities and f_a, f_b and f_c be the frequencies for the curves A, B and C respectively, then

Saturation current for B and C is same, so, Intensity of photons in B and C is same.

${\mathrm{I}}_{\mathrm{a}}={\mathrm{I}}_{\mathrm{c}}$

The Saturation current for A is lesser than that of B and C, so, ${\mathrm{I}}_{\mathrm{a}}<{\mathrm{I}}_{\mathrm{b}}={\mathrm{I}}_{\mathrm{c}}$

Stopping potential for A and B is same, so, frequency of A and B is same.

${\mathrm{f}}_{\mathrm{a}}={\mathrm{f}}_{\mathrm{b}}$

The magnitude of stopping potential for C is larger than that of A and B, so, ${\mathrm{f}}_{\mathrm{c}}>{\mathrm{f}}_{\mathrm{a}}={\mathrm{f}}_{\mathrm{b}}$.