Photo Electric Effect
=> given by H. Hertz(1887)
=> When a beam of light strike a metal surface then electrons were ejected. This phenomena is known as photo electric effect.
1. Electrons ejected from metal surface when beam of light strike the metal surface
2. Number of electron ejected is directly proportional to intensity (or brightness) of light
3. There is characteristic minimum frequency (n0threshold frequency) below which photoelectric effect is not observed.
4. If n> n0then electrons comes out with kinetic energy which increases with increase in frequency of light.
Kinetic energy of ejected electrons is given by-
h n= h n0+ ½(meV2)