A beam of light inside water strikes the water–air surface. The limiting angle of incidence in water for which the light just emerges into air is found to be 48∘.
(a) Calculate the refractive index of water with respect to air, given that the limiting angle of incidence in water is 48∘.
(b) Using the value obtained in (a), find the speed of light in water. Take the speed of light in vacuum as 3.0×108m s−1.
(c) A fish at a depth sends a ray towards the surface at an angle of incidence of 30∘ inside water. State, with reason, whether this ray will emerge into air or be totally internally reflected.