The angle of refraction is the angle between the refracted ray and the normal line, measured from the normal line to the refracted ray.
The angle of refraction can be calculated using Snell's Law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the indices of refraction of the two materials.
The angle of incidence and the angle of refraction are related by Snell's Law. As the angle of incidence increases, the angle of refraction also increases, and vice versa.
When light passes from one medium to another, the angle of refraction changes due to the change in the speed of light in the different mediums. This change in speed causes the light to bend as it enters and exits the medium.
The critical angle is the angle of incidence at which the angle of refraction is 90 degrees. If the angle of incidence is greater than the critical angle, total internal reflection occurs instead of refraction.