00:01
Hi there, so for this problem, we are asked to determine the maximum angle theta, for which the light rates incident on the end of the light pipe, are subjected to the total internal reflection along the walls of the pipe.
00:20
So we need to assume that it has an index of refraption that is equal to 1 .36, and the upside median is er.
00:35
So the situation that we have in here is, as is shown in this figure right here.
00:44
So what we need to determine first is the critical angle for this material in earth.
00:52
So we know that that critical angle, that this is, that critical angle, is going to be equal to the sign of minus one of the index of a fracture of, earth divided by the indusal refruption of the pipe that we are given that value.
01:11
So that is the formula to calculate the critical angle.
01:15
So we will have that this is the sign of minus 1 of the index of refruption of the earth divided by the index of refruption of the pipe, which is 1 .36.
01:27
So from this we obtain a critical angle equals to 47 .3 .3.
01:38
Degrees.
01:41
We know that the critical angle or the well the refrapted angle, this one right here, and it's going to be equal to 90 degrees minus the critical angle...