Einstein's Photoelectric Equation is :

K_max = hv - Φ

where v is the frequency of the incident radiation and K_max is the maximum possible kinetic energy of photoelectron. The work function Φ is given as :

Φ = hv₀ . In terms of stopping potential, K_max = eV_0.

What kind of graph do you expect between the stopping potential and the frequency of the incident radiation?

straight line with y-intercept

Compare the equation with y=mx+c