Question

Question 2.46 Nitrogen laser produces a radiation at a wavelength of 337.1 nm. If the number of photons emitted is 5.6 × 10^24, calculate the power of this laser.

Class XI Structure of Atom Page 67

Answer 1

we know,
energy of one photons ,
E = hc/λ
where, h is Plank's constant,
c is the speed of light and λ is the wavelength of photons .

Here,
λ = 337.1 nm = 3.371 × 10^-7 m
h = 6.626 × 10^-34 Js
c = speed of light

E = 6.626 × 10^-34 × 3 × 10^8/3.371 × 10^-7 J
= 0.05896 × 10^-17 J

now , energy of 5.6 × 10^24 photons = 0.05896 × 10^-17 × 5.6 × 10^24 J
= 0.3302 × 10^7 J
= 3.302 × 10^6 J

hence, power of laser = total energy of photons emitted from laser = 3.302 × 10^6 J