Question

what are law of refraction​

Answer 1

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• the principle that for a ray, radar pulse, or the like, that is incident on the interface of two media, 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 velocity of the ray in the first medium to the velocity in the second medium and the incident ray, ...

Answer 2

According to laws of refraction (Snell's Laws):
The incident ray, the refracted ray and the normal at the point of incidence, all lie in the same plane.
The ratio of the sine of the angle of incidence i to the sine of the angle of refraction is constant for the pair of given media. This constant is called the refractive index of the second medium w.r.t. the first medium.
1
​
μ
2
​
=
sin r
sin i
​

Note:
When light ray is incident normally, only speed changes and direction of light remains the same.
When light ray passes from rarer medium to denser medium, it bends towards the normal.
When light ray passes from denser medium to rarer medium, it bends away from the normal.