A Laser Emits a Pulse of Light That Lasts 10

Question 45
Multiple Choice

A laser emits a pulse of light that lasts 10 ns.The light has a wavelength of 690 nm,and each pulse has an energy of 480 mJ.How many photons are emitted in each pulse? (c = 3.0 × 108 m/s,h = 6.626 × 10-34 J ∙ s) A)1.7 × 1018 B)2.1 × img C)2.6 × img D)3.1 × img