Monochromatic light of frequency $6 \times 10^{14} \,Hz$ is produced by a laser. The power emitted is $2 \times 10^{-3} \,W$. The energy of the photon in this light beam is . . . . . . eV.

The momentum of a photon is $3.3 \times 10^{-29} \ kg \ m/s$. Its frequency will be

$A$ photon of wavelength $4400 \, \mathring{A}$ is passing through vacuum. The effective mass and momentum of the photon are respectively

The ratio of the power of a light source $S_1$ to that of the light source $S_2$ is $2$. $S_1$ is emitting $2 \times 10^{15}$ photons per second at $600 \ nm$. If the wavelength of the source $S_2$ is $300 \ nm$,then the number of photons per second emitted by $S_2$ is . . . . . . $\times 10^{14}$.

Let $n_r$ and $n_b$ be respectively the number of photons emitted by a red bulb and a blue bulb of equal power in a given time.

$A$ photon is associated with .........