Write information about negative electric charge emitted from metals when UV light is incident in them or metal are heated.

Explanation

In 1887 ,it was observed that when ultraviolet light in incident on metal or when some metals are heated negative charge is emitted methods from them.
Particles produced by different methods have similar nature.In 1897 J.J Thomson called it as electron and showed that electron is fundamental and universal particle particle .For invention of electron J.J Thomson was awarded Nobel prize of physics in 1906.
In 1913 American Scientist R.A. Millikan measured charge of eletron by oil drop experiment.He observed that charge on any oil experiment.He observed that charge on any oil drop is in integral multiple of fundamental charge `1.502xx10^(-19)`C.Thus ,Millikan proved that electric charge is in quantised from.
From specific charge `(e)/(m)` mass of electron (m) can be obtained.