2.46 Nitrogen laser produces radiation at a wavelength of 337.1 nm. If the number of photons emitted is 5.6 × 1024, calculate the power of this laser.

Power of laser = Energy with which it emits photons
Power = E = Nhcλ

Where, 

N = number of photons emitted
h = Planck’s constant
c = velocity of radiation
λ = wavelength of radiation
Substituting the values in the given expression of Energy (E):

E = 5.6 x 10246.626 x 10-34 Js3 x 108 m/s337.1  x 10-9 m
= 0.3302 x 107 J
= 3.33 x 106 J

Hence, the power of the laser is 3.33 × 106 J.