Write information about negative electric charge emitted from metals when $UV$ light is incident on them or metals are heated.
Write information about negative electric charge emitted from metals when $UV$ light is incident on them or metals are heated.
In $1887$, it was observed that when ultraviolet light is incident on metal or when some metals are heated negative charge is emitted 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. 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 electron by oil drop experiment. He observed that charge on any oil drop is in integral multiple of fundamental charge $1.602 \times 10^{-19} \mathrm{C}$. Thus, Millikan proved that electric charge is in quantised form.
From specific charge $\frac{e}{m}$, mass of electron $(m)$ can be obtained.
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