Light refracts whenever it travels at an angle into a substance with a different refractive index (optical density). This change of direction is caused by a change in speed. ... When light travels from air into water, it slows down, causing it to change direction slightly. This change of direction is called refraction.

What conditions must be present for refraction takes place?

2 a) Refraction takes place because light travels at different speeds in different mediums. When a light wave hits a new medium at an angle (not along the normal), the front part of the wave changes speed while the far side side of the wave does not. This causes the light wave to bend as it enters a new medium.

Why does reflection and refraction occur?

Reflection and refraction occur when a light hits a boundary between two media with different light speeds. When the light is split, part of it will be reflected and another part will be refracted. ... Total internal reflection occurs when there is a change in slow moving medium to a faster moving medium.