Question

In reflection, angle i=angle r, therefore when a ray strikes surface normally angle i=0 and angle r=0. But there is no such rule in refraction(i=r). So,why, when a ray strikes the surface of separation of 2 media normally,it suffers no refraction?

Answer 1

No, there is one rule in refraction also, snell’s rule:

sine(angle of incidence)*index of refraction of the incident medium=sine(angle of refraction)* index of refraction of the refractive medium

N_{1 *} sinx = N_{2 *} siny

Since angle of incidence is 0 degrees, sin(0)=0.
So, N_{2 *} siny is also zero Now, index of refraction of the refractive medium cannot be 0, so angle of incidence would be equal to 0.

So, we get the result that the light ray will pass without any deviation i.e. at o degrees.