Question

A source (100w) of light is emitting light of wavelength 6000A. Find the number of Photons emitted per second​

Answer 1

The energy of the light E=

λ

hc

​

=

6000×10

−10

(6.62×10

−34

)(3×10

8

)

​

=3.31×10

−19

J

We know that power is the energy per second. Thus, the energy per second is given 100J

Thus, number of photons per second =

3.31×10

−19

100

​

=3.02×10

20

∼3×10

20