Question

A 100W sodium lamp radiates energy uniformly
in all directions. The lamp is located at the centre of
a large sphere that absorbs all the sodium light which
is incident on it. The wavelength of the sodium light
is 589 nm. At what rate are the photons delivered to the sphere?

Answer 1

Explanation:

Ans : 2.96×1020photon/s

Energy per photon in light, E=hc/λ=(6.626×10−34×3×108)/(589×10−9)=3.37×10−19J

No. of photons delivered to the sphere =P/E

=100/(3.37×10−19)=2.96×1020photon/s