what is stopping potential ? how does the frequency effect it ? explain

The stopping potential V_c is found to be changing linearly with frequency of incident light being more negative for high frequency. An increase in frequency of the incident light increases the kinetic energy of the emitted electrons, so greater retarding potential is required to stop them completely. For a given frequency v, V_c measures the maximum kinetic energy E_max of photoelectrons that can reach plate C.

 eV_c = 1/2 mV²_max

Where m is the mass of electron, e is charge of electron and V_max is maximum velocity of electron. This means that work done by stopping potential must just be equal to maximum kinetic energy of an electron.