Question

A beam of light passes from water through a thin layer of oil and into air, as shown in the image below. If the incident angle in the water is 20° (the picture is not to scale), at what angle of refraction will the light beam pass from the oil to the air? Show your work and explain your reasoning. The index of refraction of water is 1.33 and the index of refraction of oil is 1.55.

Picture Link: https://ibb.co/JqGYLpj

Answer 1

$\frac{\sin\theta}{\sin\varphi}=\frac{n_o}{n_w},$ $\frac{\sin\varphi}{\sin\phi}=\frac{n_a}{n_o},$

$\phi=\arcsin(\frac{n_w}{n_a}\sin \theta)=27°.$