The approximate wavelength of a photon of energy $2.48 \,eV$ is ............ $\mathring A$.

Write the equation for the effective mass of a photon.

In the Compton scattering process,the incident $X$-radiation is scattered at an angle of $60^{\circ}$. The wavelength of the scattered radiation is $0.22 \ \text{Å}$. The wavelength of the incident $X$-radiation in $\text{Å}$ units is:

The Compton effect supports the fact that

$A$ laser produces a beam of light of frequency $5 \times 10^{14} \,Hz$ with an output power of $33 \,mW$. The average number of photons emitted by the laser per second is (Planck's constant $h = 6.6 \times 10^{-34} \,J \,s$)

$A$ photon has a wavelength of $3 \,nm$. Its momentum and energy, respectively, will be:
$[h = 6.63 \times 10^{-34} \,Js, c = 3 \times 10^8 \,m/s]$