From Einstein's photoelectric equation the maximum kinetic energy of photoelectrons emitted from metal surface is EK and W is work function, then EK=hv−W
If v0 is threshold frequency, then W=hv0 ∴EK=hv−(hv)0=h(v−v0)
From the above equation, it is clear that maximum kinetic energy of electron will increase almost linearly with increase in the frequency of the incident light.