Question

A coin is placed at the bottom of a tin can. Move your eyes until the coin is just out of sight (see diagram). Keep your eyes in this position while someone pours water gradually into the tin can. What would you observe ? Explain your observation.

Answer 1

When water is poured then it is due to refraction of light taking place that the coin becomes visible.

Let a coin be placed in an opaque container which is not visible since the light rays from the coin travelling in straight lines are blocked by the walls of the container. When water is poured, light travels in a straight line until it reaches the surface of water, then it bends. When produced backwards this ray appears to come from the position C '. Since the point C' is at a higher level than C, the coin appears raised and becomes visible.