Q.
The photosensitive surface is receiving the light of wavelength 5000A∘ at the rate of 10−8Js−1. The number of photons received per second is ( h=6.62×10−34Js,c=3×108ms−1 )
Energy of photon E=λhc
Given, λ=5000Å=5×10−7m ∴E=5×10−76.6×10−34×3×108 =3.96×10−19J
Energy received per second = 10−8Js−1 ∴ Number of photon's received per second
= EnergyofonephotonEnergyreceivedpersecond
= 3.96×10−1910−8=2.5×1010