How does the maximum kinetic energy of electrons emitted vary with the work function of the metal??
Let a monochromatic light of frequency ν be incident on the surface of a metal of work function Ø. The energy of a photon in the light is, E = hν. When a photon strikes a free electron the surface of the metal, the electron gets an extra energy E = hν and may come out of the metal. The electron trying to escape the surface will be attracted by the surface with a force equal to Ø. So, the maximum KE of the electron is given by,
KE = hν – Ø
Since, for a monochromatic light hν is a constant. The graph for KE versus Ø is a straight line with a negative slope.
The graph signifies the dependence of KE of an emitted electron on the work function of the metal.
The Maximum KE of an emitted electron decreases with the increase in work function of the metal.