When suitably cut and mounted between glass cover-slips, naphthalene crystals exhibit the phenomena of conical refraction in a very striking way, and enable their features to be critically examined.

A ray diagram showing refraction at the boundary between air and glass Refraction can cause optical illusions as the light waves appear to come from a different position to their actual source.

It is refraction that makes some objects appear to bend when they are viewed through water, like the straw shown here. If the light hits the surface of a glass block at an angle, this change in ...

Refraction occurs when light changes direction as it passes, e.g., from air into water or glass. Negative refraction, however, is a counterintuitive effect where light in a medium bends in the ...