Question

A monochromatic source of light operating at 200W
emits 4 xx (10^20) photons per second. Find the wavelength
of the light.

Answer 1

Answer:

E=nhc/λ

for 1s E=P

200= 4 * 10^20 *hc/λ

λ=2*10^18*hc

put h=6.63*10^-34 and c=3*10^8

λ=3.98*10^-7 metre