# A special kind of light bulb emits monochromatic light of wavelength 700nm. Electrical energy supply to it at the rate of 60W and the bulb is 50% efficient at converting that energy to light energy. How many photons are emitted by the bulb during its life time of 1 day? (Give me solution using formula )

Arun
25763 Points
4 years ago
Dear Preeti

As we know
n *h* $\nu$ = P
n = P/h$\nu$ = P$\lambda$/ hc
On putting the values
n = 2.1 * 10^20 photons/sec
Since efficiency = 50%
Hence
50% of n = 1.05 * 10^20 photons/sec