In certain cases, light may be viewed as a stream of particles termed photons. Each photon carries a linear momentum h/ , where h is Planck's constant and is the wavelength of the light. A beam of light having wavelength strikes a plane mirror at an angle of incidence . Determine the change in a photon's linear momentum when the beam undergoes reflection by the mirror.

Step-by-step solution

The magnitude of the initial momentum of the photon is p = h . Let the normal to the mirror be along the y-axis. The incident photon makes an angle of incidence with the normal. The components of the initial momentum p _i are: p_ ix = p p_ iy = -p After reflection, the angle of reflection is equal to the angle of incidence . The components of the final momentum p _f are: p_ fx = p p_ fy = p The change in momentum is given by p = p _f - p _i . p_x = p - p = 0 p_y = p - (-p ) = 2p The magnitude of the change in linea