00:01
So for our question, we're told that we have a ray of light going from air to glass, where the index of refraction of glass, which i call n -sub -g is 1 .56.
00:11
It also tells us that the angle of refraction is half the angle of incident, or theta -1 is equal to 2, theta -2.
00:20
So using snells law, we can then find the angle of incident, and it gives us the hint of using that trigonometric identity there, which we are going to make use of.
00:31
So snell's law here says n1 times the sign of the incident angle, which we're going to call 2 theta.
00:38
So this data term is what we're going to find here is equal to, in our situation, n2 times the sign of theta.
00:50
Okay.
00:51
So here, n1 is air, so we can replace that with n sub a times the sign of 2 theta is equal to n sub g.
01:05
That's our second medium times the sine of theta.
01:10
Well, that trigonometric identity says that sine 2 theta is equal to 2 times the cosine of theta multiplied by the sine of theta.
01:22
And i'm going to divide both sides by the index every fraction of air, which is equal to 1.
01:27
So anything divided by 1 is just itself...