Light and Optics: Refraction, Snell’s Law, and Pinhole Imaging

A beam of light travels from air ($n_1 = 1.000$) into plastic ($n_2 = 1.540$) with an angle of incidence $\theta_1 = 55^\circ$. What is the angle of refraction $\theta_2$ in the plastic? Use Snell's Law.

Given the indices of refraction: Air ($n = 1.000$), Fiberglass ($n = 1.56$), and Milk ($n = 1.35$), a light ray enters from air into fiberglass at $30^\circ$ to the normal. What is the angle of refraction in the fiberglass?

A light ray passes from fiberglass ($n = 1.56$) into milk ($n = 1.35$) with an angle of incidence of $20^\circ$. What is the angle of refraction in the milk?