Bose-Einstein statistics is applicable to particles with

Number of photons of equal energy emitted per second by a $6 \ mW$ laser source operating at $663 \ nm$ is . . . . . . . (Given: $h=6.63\times10^{-34} \ J.s$ and $c=3\times10^{8} \ m/s$)

Light from a source travels out with a velocity $c$. If the source moves away from the observer with a velocity $v$,then the relative velocity of light with respect to the observer is

The principle of $LASER$ action involves:

The radiant energy from the Sun incident on the Earth's surface is $2 \ cal/cm^2 \cdot min$. If the average wavelength of solar radiation is $5500 \ \mathring A$,then the number of photons incident per minute on a surface area of $1 \ cm^2$ on the Earth's surface is ............ $(h = 6.6 \times 10^{-34} \ J \cdot s, 1 \ cal = 4.2 \ J)$

What is the momentum of a photon having frequency $1.5 \times 10^{13} \ Hz$?