00:01
In this problem we are having a pipe like this with some thickness and the length is given as 42 cm and this is given at 3 .1 millimeter.
00:26
So now the angle of this angle is given as 50 degrees.
00:32
Okay? the angle of incidence is given as 50 degrees.
00:38
So the angle of refraction, as this is denser, this ray will move towards the normal.
00:50
So this angle is actually the angle of refraction.
00:53
So for all the other surfaces, i mean this angle will be the angle of incidence for all the other surface.
01:01
So it will go on like this.
01:03
Again, it will go on like this.
01:05
So it will go on like this.
01:06
And ultimately it will go outside the tube.
01:11
So that means we need to first calculate this angle actually.
01:15
What is this angle? so you can see it is given that the risk, and it practically is 1 .4.
01:22
So this angle is actually nothing but 90 degrees minus r.
01:27
So actually this angle, let's say this angle is theta.
01:30
So theta is 90 degree minus sine inverse of sine 50 divided by 1 .48 because this is actually the angle of refraction, sine inverse sine 50 by 1 .48.
01:49
So 90 degrees minus angle of refraction is theta.
01:53
So this is coming approximately 58 .83 degree, okay? so this is the this angle...