?The momentum of light, as it is for particles, is exactly reversed when a photon is

Chapter 6, Problem 141

(choose chapter or problem)

The momentum of light, as it is for particles, is exactly reversed when a photon is reflected straight back from a mirror, assuming negligible recoil of the mirror. The change in momentum is twice the photon’s incident momentum, as it is for the particles. Suppose that a beam of light has an intensity \(1.0 \mathrm{~kW} / \mathrm{m}^{2}\) and falls on a \(-2.0-\mathrm{m}^{2}\) area of a mirror and reflects from it. (a) Calculate the energy reflected in 1.00 s. (b) What is the momentum imparted to the mirror? (c) Use Newton’s second law to find the force on the mirror. (d) Does the assumption of no-recoil for the mirror seem reasonable?

Text Transcription:

1.0 kW/m^2

-2.0m^2