The number of photons of wavelength 540 nm emitted per second by an electric bulb of power 100W is (taking h = h=6×10−34J−sec )
100
1000
3×1020
3×1018
p=nhcλt⇒100=n×6×10−34×3×108540×10−9×14⇒n=3×1020
A bulb emits light of wavelength 198 nm. The bulb is rated as 100 watt and 10 % of the energy is emitted as light. The number of photons emitted per second is 10x. Take h=6.6×10−34. The value of x is