The incident ray comes at 30 degrees to normal at the air/glass boundary and is refracted at 18 degrees to normal. a) find index of refraction of glass b)find speed of light in glass c) under what conditions and for what angles will you have total internal reflection in this system (hint consider all paths for incident ray)
a)I'm not completely sure about this question but would I do this:
sin theda 1/sin theda 2 = n2 (where n2 is the index of refraction of the glass)
b)v=c/n =3x10^8m/s/(answer from part a)
c)theda critcal = arcsin(n2/n1) and again you would what ever number n would be from part a) and n2=a because that is the index of refraction of air
Is this setup correct? I am sure that b) and c) are but part a) is the part that is confusing.
Yes, your setup is correct for parts b) and c). Let's break down part a):
When light passes from one medium to another, it undergoes refraction, which is the bending of light due to the change in speed as it travels from one medium to another. The index of refraction is a measure of how much the speed of light changes when it passes through a medium.
In this case, the incident ray is coming from air and entering the glass medium. We know the angle of incidence (the angle between the incident ray and the normal) is 30 degrees, and the angle of refraction (the angle between the refracted ray and the normal) is 18 degrees. We can use Snell's law to find the index of refraction of glass.
Snell's law states: n1 * sin(theta1) = n2 * sin(theta2)
where n1 and n2 are the indices of refraction of the two media, and theta1 and theta2 are the angles of incidence and refraction, respectively.
In this case, n1 is the index of refraction of air, which is approximately 1. We are trying to find n2, the index of refraction of glass.
Using the given information, we can set up the equation:
1 * sin(30 degrees) = n2 * sin(18 degrees)
Now, solve for n2:
n2 = (1 * sin(30 degrees)) / sin(18 degrees)
Using a calculator, we find that n2 is approximately 1.503.
Therefore, the index of refraction of glass is approximately 1.503.