Question

Radiation power of 3.31 Watt is falling on a surface. If 20% of light is absorbed
and remaining is reflected back, calculate number of photons reflected per second.
Take the frequency of each photon 1012 Hz. and h=6.62x10-34 J-s
​

Answer 1

Answer:

Power of the source = 62 watt

Energy emitted in a second = 62 joules

So, number of photons emitted in a second =

hC

62λ

=

6.626×10

−34

×3×10

8

62×4800×10

−10

photons / sec

=1.4962×10

20

photons / sec

≈1.5×10

20

photons /sec