Question

A laser emits light that has a frequency of 6.69 x 1014 s-1. If the laser emits a "pulse" (a burst of light) that contains 7.0 x 1017 photons, what is the total energy of that pulse in Joules? Do not use scientific notation in your answer. Give the answer ( in Joules) to 2 significant figures.

Answer 1

0.31 Joule

Step-by-step explanation:

ΔE(per photon) = h·f = (6.63 x 10⁻³⁴J·s)(6.69 x 10¹⁴s⁻¹) = 4.44 x 10⁻¹⁹ J/photon X 7 x 10¹⁷photons = 0.31 Joules