Physics
Physics
Problem
Unpolarised light of wavelength is incident from air on a glass surface of refractive index . The light reflected from the surface is analysed with a Polaroid sheet. a. (a) Calculate the angle of incidence for which the reflected beam is completely plane-polarised. b. (b) At the angle found in part (a), state the direction of the electric field vector of the reflected beam with respect to the plane of incidence. c. (c) If the reflected beam has intensity and passes through a Polaroid whose transmission axis makes an angle of with the direction of the electric field in the beam, determine the intensity of light transmitted by the Polaroid.Intuitive explanation
When unpolarized light reflects off a dielectric surface, the reflected beam becomes partially polarized—more of one orientation survives than the other. This happens because -polarized light (parallel to the plane of incidence) reflects differently than -polarized light (perpendicular to it), especially near Brewster's angle, where -polarized reflection vanishes entirely. To find what the Polaroid reveals, calculate Brewster's angle using the refractive indices, then determine how much of each polarization component actually reflects at your incident angle.
Intuitive explanation
When unpolarized light reflects off a dielectric surface, the reflected beam becomes partially polarized—more of one orientation survives than the other. This happens because -polarized light (parallel to the plane of incidence) reflects differently than -polarized light (perpendicular to it), especially near Brewster's angle, where -polarized reflection vanishes entirely. To find what the Polaroid reveals, calculate Brewster's angle using the refractive indices, then determine how much of each polarization component actually reflects at your incident angle.