A Helium-Neon Laser Emits Red Light Having a Wavelength of 632.8

Multiple Choice

A helium-neon laser emits red light having a wavelength of 632.8 nm and a power of 10 mW.How many photons are emitted each second? (h = 6.63 × 10−³⁴ J⋅s,c = 3.00 × 10⁸ m/s,and 1 nm = 10−⁹ m)

A) 4.8 × 10¹⁷
B) 1.6 × 10¹⁵
C) 3.2 × 10¹⁶
D) 2.6 × 10¹⁸