A monochromatic laser in air produces a beam of intensity and vacuum wavelength
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics
Problem
A monochromatic laser in air produces a beam of intensity 2.0×103W⋅m−2 and vacuum wavelength 550nm. The beam is initially polarized at 0° (horizontal). The beam passes sequentially through three ideal polarizers whose transmission axes are oriented at 20°, 65°, and 100° relative to the horizontal, respectively. Immediately after the third polarizer the beam enters a glass plate (nglass=1.50) at normal incidence. On the far side of the plate the beam enters a water tank (nwater=1.33) at normal incidence.
Neglect reflection losses except those explicitly discussed.
(a) Calculate the intensity of the beam after each of the three polarizers.
(b) Using appropriate wave principles, determine the wavelength of the light while it is inside the glass and while it is inside the water.
(c) For each of the two interfaces (air–glass and glass–water), state whether a reflected wave is inverted or non-inverted relative to the incident beam and justify each answer.
(d) Two successive reflections occur when a portion of the beam reflects from the front surface of the glass, travels to the glass–water interface, reflects again, and re-emerges into air. Discuss whether the double-reflected beam is overall inverted or non-inverted relative to the original incident beam, and explain your reasoning.