The momentum of a photon of energy $h\nu$ will be:

The value of Planck's constant is

The particle having zero rest mass is

Monochromatic light of frequency $6.0 \times 10^{14} \text{ Hz}$ is produced by a laser. The power emitted is $2 \times 10^{-3} \text{ W}$. The number of photons emitted,on the average,by the source per second is

When an $X$-ray photon collides with a proton,its frequency:

$A$ bulb has a power of $60 \, mW$ and emits light of wavelength $6000 \, \mathring{A}$. Calculate the number of photons emitted by the bulb per second.