The frequency of a photon having energy $66 \ eV$ is:

What is the energy and momentum of a photon having frequency $v$?

There are two sources of light,each emitting with a power of $100 \, W$. One emits $X$-rays of wavelength $1 \, nm$ and the other visible light at $500 \, nm$. Find the ratio of the number of photons of $X$-rays to the photons of visible light of the given wavelength.

If $E$ and $P$ are the energy and the momentum of a photon respectively,then on reducing the wavelength of the photon:

$A$ $60 \,W$ source emits monochromatic light of wavelength $662.5 \,nm$. The number of photons emitted per second is

The momentum of a photon with frequency $1.5 \times 10^{13} \ Hz$ is .......