How many photons are produced in a laser pulse of 0.281 j at 531 nm?

7.51 × 10¹⁷

Explanation:

1. Calculate the energy of one photon

The formula for the energy of a photon is

E = hc/λ  

h = 6.626 × 10⁻³⁴ J·s; c = 2.998 × 10⁸ m·s⁻¹

λ = 531 nm = 531 × 10⁻⁹ m                                Insert the values

E = (6.626 × 10⁻³⁴ × 2.998× 10⁸)/(531 × 10⁻⁹)

E = 3.741× 10⁻¹⁹ J

2. Calculate the number of photons

Divide the total energy by the energy of one photon.

No. of photons = 0.281 × 1/3.741 × 10⁻¹⁹

No. of photons = 7.51 × 10¹⁷ photons