Question

the law of refraction at plane surface​

Answer 1

here is your answer

hope you get this

Answer 2

$\textbf{Law of Refraction }$:

Law 1 :

The incident ray, the refracted ray and the normal to the surface separating the two media all lie in the same plane.

Law 2 :

The ratio of the sine of the angle of incidence to the sine of the refractive angle is constant for a pair of media.

Sin i / Sin r = constant

The constant is also known as Thw refractive index of the medium. This Law is also known as Snell's Law.