The principle of $LASER$ action involves:

$A$ transmitter of power $10 \text{ kW}$ emits radio waves of wavelength $500 \text{ m}$. The number of photons emitted per second by the transmitter is of the order of:

The energy of a photon is $E = h\nu$ and the momentum of a photon is $p = \frac{h}{\lambda}$. The velocity of the photon is:

According to the modern theory of the nature of light,light has ...

Monochromatic light of frequency $6.0 \times 10^{14} \;Hz$ is produced by a laser. The power emitted is $2.0 \times 10^{-3} \;W$.
$(a)$ What is the energy of a photon in the light beam?
$(b)$ How many photons per second,on an average,are emitted by the source?

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