Question

what is the number of photons of light with a wavelength 4000 pm that provide 1 joule of energy?​

Answer 1

Explanation:

The wavelength of light is 4000pm or 4000×10

−12

m or 4000×10

−9

m.

The energy one photon is

λ

hc

=

4×10

−9

6.626×10

−34

×3×10

8

=4.97×10

−17

.

The number of photons that will provide 1 J of energy is

4.97×10

−17

1J

J=2.01×10

18

.