Final answer:
The index of refraction for the window is calculated using Brewster's Law and the given polarization angle of 55.6°, resulting in an index of 1.50 which indicates that the window is likely made of crown glass.
Step-by-step explanation:
The phenomenon in which light reflected at a certain angle becomes completely polarized is known as Brewster's Law. According to Brewster's Law, the polarization occurs when the reflected and refracted rays are at a right angle to each other. The angle at which this happens is known as Brewster's angle (θ_b), and it can be used to calculate the index of refraction (n) of a material by using the formula n = tan(θ_b). Given that the light is polarized at a 55.6° angle when reflected from window glass, we can calculate the index of refraction by taking the tangent of 55.6°. Doing so, we get n ≈ 1.50. Among the given options, the substance that has an index of refraction of 1.50 is crown glass. Therefore, the window is likely made of crown glass.