The fact that electric charges are integral multiples of the fundamental electronic charge was proved experimentally by
Planck
J.J. Thomson
Einstein
Millikan
What is charge on an electron ?
Electric field and magnetic field in Thomson mass spectrograph are applied
Who invented $X-$ rays?
Which particles are responsible for conductivity of metals ?
In Bainbridge mass spectrograph a potential difference of $1000 V$ is applied between two plates distant $1$ cm apart and magnetic field in $B = 1T$. The velocity of undeflected positive ions in m/s from the velocity selector is