# Nitrogen laser produces a radiation at a wavelength of 337.1 nm.

Question.

Nitrogen laser produces a radiation at a wavelength of $337.1 \mathrm{~nm}$. If the number of photons emitted is $5.6 \times 10^{24}$, calculate the power of this laser.

Solution:

Power of laser = Energy with which it emits photons

Power $=E=\frac{\text { Nhe }}{\lambda}$

Where,

N = number of photons emitted

h = Planck’s constant

c = velocity of radiation

$\lambda=$ wavelength of radiation

Substituting the values in the given expression of Energy (E):

$E=\frac{\left(5.6 \times 10^{24}\right)\left(6.626 \times 10^{-34} \mathrm{Js}\right)\left(3 \times 10^{8} \mathrm{~ms}^{-1}\right)}{\left(337.1 \times 10^{-9} \mathrm{~m}\right)}$

$=0.3302 \times 10^{7} \mathrm{~J}$

$=3.33 \times 10^{6} \mathrm{~J}$

Hence, the power of the laser is $3.33 \times 10^{6} \mathrm{~J}$.

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