A particle which has zero rest mass and non-zero energy and momentum must travel with a speed
Equal to $c$, the speed of light in vacuum
Greater than $c$
Less than $ c$
Tending to infinity
According to Einstein's photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is
Photons of energy $6 eV$ are incident on a metal surface whose work function is $4 eV$. The minimum kinetic energy of the emitted photo-electrons will be ........... $eV$
A 1$\mu$ $A$ beam of protons with a cross-sectional area of $0.5$ sq. mm is moving with a velocity of $3 \times {10^4}m{s^{ - 1}}$. Then charge density of beam is
Which one of these is non-divisible