Energy of a photon is $1 \ MeV,$ then its momentum will be $:-$

What is the wavelength for a wave having frequency $50 \ Hz$?

The electron is

The wavelength of photon $A$ is $400 \ nm$. The frequency of photon $B$ is $10^{16} \ s^{-1}$. The wave number of photon $C$ is $10^{4} \ cm^{-1}$. The correct order of energy of these photons is:

If light waves pass through a $Nicol$ prism,then all the oscillations occur only in one plane. Such a beam of light is called:

It is observed that characteristic $X$-ray spectra of elements show regularity. When frequency to the power '$n$' i.e.,$v^{n}$ of $X$-rays emitted is plotted against atomic number '$Z$',the following graph is obtained. The value of '$n$' is