Why is wave theory of electromagnetic radiation not able to explain photo electric effect? How does photon picture resolve this problem?
Answers
According to Maxwell's theory of electricity and magnetism Light is an electromagnetic wave and hence it is unable to answer the mechanism behind the photo electric effect.
The reason for this is as follows
1)A wave doesn't possess momentum and therefore according to Maxwell's theory of electricity and magnetism Light had no momentum .
2)If light does not have momentum then how did the photo electric effect took place? This was a contradiction and einstein was the one to solve this contradiction.
3)According to einstein light came in quantized (small ) parts and each such part is known photons.
4)Each photon can be considered as a particle and since it is a particle it has momentum .
5)Momentum of light was calculated using the formula momentum =h/wavelength .
6)By assuming light as photons we can easily assume that it can knock out an electron from an atom.