Calculate the number of photons, from green light of mercury (ʎ = 4961 Å), required to do one joule of work?

2.4961/m^3

4524.2×10^18/m^3

2.4961×10^18/m^3

None of these

Energy of one photon (E) = hc / λ

h = 6.626 × 10^-34 Js

c = 3 × 10^8 m/s

λ = 4961 Å = 4961 × 10^-10 m

E = (6.626 × 10^-34 Js × 3 × 10^8 m/s) / (4961 × 10^-10 m)

= 4.007 × 10^-19 J

Number of photons required to do 1 J of work:

n = 1 J / (4.007 × 10^-19 J)

= 2.4961 × 10^18