00:01
All right, so if we have total internal reflection, let's assume we have two media.
00:04
Let's call this in 1, or medium 1 and medium 2, with their respective indices of refraction.
00:09
Let's say this is our normal direction relative to the interface.
00:13
Light in medium 1 entirely reflects off the boundary with medium 2.
00:17
So if you have light coming in, like here, it just kind of goes this way.
00:22
It doesn't actually be, it's not transmitted.
00:25
And so what do we need for that to be true? so what we'll do is we'll take our angle of medium 2 to be 90 degrees.
00:32
We use snell's law, which says n1 times the sign of theta 1, which i'll say this is theta 1, is equal to n2 times the sign of 90, which is just 1.
00:43
In fact, sorry, let's call this the critical angle...