Index of refraction of the plexyglass

[dsafla]

If

Sin(theta r)/Sin(theta i) is reversed from Sin(theta i)/Sin(theta r) = n, what does this mean? I'm quite confused since I'm doing a physics lab, and the class was told to make a graph where we measured angles with polar paper, pins and plexyglass. Could it possibly the index of refraction of air?

Thanks so much.

 

[Doc Al]

Snell's law

That n is the index of refraction of the plexyglass. Here's the explanation. First, Snell's law of refraction is this:
$$n_1 sin\theta_1 = n_2 sin\theta_2$$
Where 1 and 2 represent the two different media. If you are going from air (1) to plexyglass (2), then you can rewrite this as:
$$sin\theta_i = n_2 sin\theta_r$$
(Note that the index of refraction of air is n = 1.)
So... you can solve for the index of refraction of the plexyglass:
$$n_2 = \frac{sin\theta_i}{sin\theta_r}$$

 

[M98Ranger]

The index of refraction of plexiglass, also known as acrylic, is approximately 1.49. This means that light travels slower through plexiglass than it does through air, which has an index of refraction of 1. Therefore, the ratio of the sine of the angle of incidence (theta i) to the sine of the angle of refraction (theta r) is equal to the index of refraction (n).

However, if you reverse the ratio, the result would be the inverse of the index of refraction. This could potentially mean that you are measuring the index of refraction of air, as air has an index of refraction of approximately 1. The graph you are creating with the polar paper, pins, and plexiglass is likely demonstrating Snell's law, which relates the angles of incidence and refraction to the index of refraction of the material.

If you are still unsure, it would be best to consult with your instructor or a classmate for clarification. It is always important to make sure you fully understand the concepts in a lab before proceeding with the experiment. Good luck with your lab!