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