The figure shows the variation of photocurrent with anode potential 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

$f_a=f_b$ and $I_a≠I_b$

The stopping potential for curves a and b is same.

$∴f_a=f_b$

Also saturation current is proportional to intensity

$∴I_a<I_b$