00:01
So in this question there is a boundary, there is a refractive index n of a medium which is here.
00:08
Now it is given that a ray of light is incident here, which is making some angle theta here.
00:17
And now this is the light which is actually reflected.
00:24
And we know that this angle has to be theta because this is nothing but law of reflection.
00:29
So whatever angle we have, the angle of incidence, the same.
00:32
Amount of angle would be the angle of reflection.
00:36
Now here we will have another ray which is traveling into another medium.
00:42
So now this is the angle of refraction.
00:47
So if we see very carefully here, then we can see that it is given to us that the reflected light which is this light.
01:01
I'm using a different color here to you know clear it.
01:04
Reflected light which is this light and the refracted light they are actually perpendicular to each other this is given to us so now if this angle is 90 the sum of these two angle would also be 90 because total angle on a line has to be 180 degree so what does that mean that simply means that the angle are okay i'm calling here angle of refraction plus this angle here this angle here which is theta should be equal to definitely 90 degree, which implies the angle r is equal to 90 minus theta...