Question

full explaination of photoelectric effect .how it discover and its benefits

Answer 1

HI.

LENARD told that when two plates of zinc put inside the vaccum bulb and commented with battery and galvanometer then the high frequency ultra voilet Ray's falls on cathode and electron enitted from cathode which are attracted by anode the circuit connected between cathode and anode and current flows anode to cathode in circuit .
The phenomenon of emission of electrons from metals (plates ) under the effect of Light rays is called photo electric effect !
The electron enitted by Photo electric effect are called photo electrons and the current produced is called photo electric current !
It is discovered there are some optical phenomenon like interference and diffraction of light which can be explained only on the basis of Huygen's wave theory of light thus, these phenomenon support of the wavenature of light .
On the other hand these are some other phenomenon regarding light like photoelectric effect . And Compton's effect which can be explained by the basis of Planck quantom theory of light the wave theory of light is totally failed in explaining these phenomenon .
From the experimental observation we conclude that some times light behaves likes waves and see me other time it behaves like particles (photon) that is why it is set that light has dual nature !