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.

When a wave or light ray moves from one medium to another its speed changes. The direction of the ray may also change. This property of waves is called refraction and commonly occurs with light rays.

This Thursday night, for the first time in nearly two-and-a-half years, our planet's faithful companion is going to get fancy ...

“Topics like Refraction of Light and Spectrum ... been added from this year onwards,” said Acharya. “Making ray diagrams, wherever necessary, can help achieve better marks,” she added.