The photo-electric effect is the emission of electrons (called photo-electrons) when light strikes a surface. To escape from the surface, the electron must absorb enough energy from the incident radiation to overcome the attraction of positive ions in the material of the surface.
The photoelectric effect is based on the principle of conservation of energy.
(1) Work function (or threshold energy) (W0) : The minimum energy of incident radiation, required to eject the electrons from metallic surface is defined as work function of that surface.
(2) Threshold frequency (V0) : The minimum frequency of incident radiation, required to eject the electrons from metal surface is defined as threshold frequency.
V < v0
No photoelectron emission
(3) Threshold wavelength (λ0) : The minimum frequency of incident
(4) Einstein’s photoelectric equation:
E = W0 + Kmax
Where Kmax = mv2max/2 = maximum kinetc energy of emitted electrons.