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.

A ripple tank is a transparent shallow tray of water with a light shining down through it onto a white card below. The light allows you to see the motion of the ripples created on the water's ...

The researchers theorize that these far-off remnants could either be deposits of silica-rich material that have hung around ...