A light ray is moving from denser (refractive index = $\mu$) to air. If the angle of incidence is half the angle of refraction, find out the angle of refraction.

There is a small air bubble inside a glass sphere ($\mu$ = 1.5) of radius 10 cm. The bubble is 4 cm below the surface and is viewed normally from the outside as shown in figure. Find the apparent depth of the bubble.