Question

What is a critical angle?
And how is it formed?

Answer 1

Answer:

The critical angle occurs when the angle of incidence where the angle of refraction is 90°. The light must travel from an optically more dense medium to an optically less dense medium.

Answer 2

Answer:

The critical angle is defined as the angle of incidence that provides an angle of refraction of 90-degrees. Make particular note that the critical angle is an angle of incidence value. For the water-air boundary, the critical angle is 48.6-degrees.

Waves going from a dense medium to a less dense medium speed up at the boundary between them. This causes light rays to bend when they pass from glass to air at an angle other than 90°. Beyond a certain angle, called the critical angle, all the waves reflect back into the glass.

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