An oxide coated filament is useful in vacuum tubes because essentially
It has high melting point
It can withstand high temperatures
It has good machanical strength
It can emit electrons at relatively lower temperatures
Who produced electromagnetic waves for the first time ?
Cathode rays are
A charge of magnitude $3e$ and mass $2m$ is moving in an electric field $\overrightarrow E .$ The acceleration imparted to the charge is
Electric field and magnetic field in Thomson mass spectrograph are applied
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