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What causes light to refract?

Answer 1

Light enters a medium of different optical density and this causes its speed to change and hence it bends or refracts.

When light passes from an optically less dense to an optically more dense medium (example from air to glass since the refractive index #n_(air) < n_(glass)#) its speed decreases and hence it refracts towards the normal. (line drawn perpendicularly to the plane of the surface).

Light refracts toward the normal when it travels from an optically more dense medium—such as water—to an optically less dense medium—as long as the angle of incidence stays below the critical angle for both media. If it does, total internal reflection will happen.

In each case, the wave equation #v=f lambda# is still satisfied.

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Answer 2

Owen Atkinson

Light refracts when it travels from one medium to another with a different optical density, causing its speed to change, which results in a change in direction. This change in direction is due to the difference in the speed of light in the two media, according to Snell's law.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.