A 25 watt bulb emits monochromatic yellow light of wavelength of 0.57µm. Calculate the rate of emission of quanta per second.





Q.11:- A 25 watt bulb emits monochromatic yellow light of wavelength of 0.57µm. Calculate the rate of emission of quanta per second.

 

 

Answer:-
Energy emitted by the bulb = 25 watt = 25 Js-1
Energy of one photon (E) = hν = hc/λ
λ = 0.57µm = 0.57×10-6 m
E = (6.626×10-34 Js×3.0×10ms-1)/0.57×10-6 m = 3.48×10-19 J
∴ No. of photons emitted per sec = 25 Js-1/3.48×10-19 J = 7.18×1019