In Thomson's experiment if the value of $q/m$ is the same for all positive ions striking the photographic plate, then the trace would be
Straight line
Parabolic
Circular
Elliptical
The cathode rays have particle nature because of the fact that
An electron is accelerated through a potential difference of $200$ volts. If $e/m$ for the electron be $1.6 \times {10^{11}}$ $coulomb/kg$ , the velocity acquired by the electron will be
When electron beam passes through an electric field, they gain kinetic energy. If the same beam passes through magnetic field, then
In an electron gun, the electrons are accelerated by the potential $V$. If e is the charge and $m$ is the mass of an electron, then the maximum velocity of these electrons will be
Write and explain methods to obtain emission of electron from metal.