Einstein explained photoelectric effect on the basis of 'Quantum theory of radiation'.
The energy of Photon is given by
\(hv = W + 1/2mv^2\)
K.E. = \(hv - \phi_0\) ..............(1)
\(\phi_0 = hv_0\)
Substituting the value of \(\phi_0\) in equation (1) we get,
K.E.max = h(v-v0)
Observations and Conclusions by Einstein
1) Photoelectric effect is instantaneous effect and takes place due to elastic collision between photon and electron inside the metal.
2) If v<v0, then ½ mv2 max is negative, which is not possible. Therefore, for photoelectric emission to take place v > v0.
3) Since one photon emits one electron, so the number of photoelectrons emitted per second is directly proportional to the intensity of incident light.
