A light beam from a 2.1-mW He-Ne laser has a wavelength of 633 nm.How many photons does the laser emit in one second? (h = 6.626 × 10^-34 J • s,c = 3.00 × 10⁸ m/s) A) 6.7 × 10¹⁵ B) 8.8 × 10¹⁵ C) 1.1 × 10¹⁶ D) 1.3 × 10¹⁶

Question

Quizplus · Accepted Answer

The energy of a single photon is given by E = hc/λ, where h is Planck's constant, c is the speed of light, and λ is the wavelength. The number of photons emitted per second is given by P/E, where P is the power of the laser. Plugging in the given values, we get:E = (6.626 × 10^-34 J • s)(3.00 × 10^8 m/s)/(633 × 10^-9 m) = 3.14 × 10^-19 JP/E = (2.1 × 10^-3 W)/(3.14 × 10^-19 J) = 6.7 × 10^15 photons/s

A Light Beam from a 2