Question

If a light ray is traveling from an object(clear plastic) into the air, and the refractive index for air is 1.00, how can the refractive index for clear plastic be calculated

Answer 1

You can use Snell's Law that relates the angles of the ray in the clear plastic and in the air to the ratio of their refraction indexes (n):

$\frac{n_{plastic}}{n_{air}} =\frac{\sin\theta_{air}}{\sin\theta_{plastic}}$

If you measure the two angles by experiment, then you can calculate the index of refraction of the clear plastic:

$n_{plastic} =n_{air}\cdot\frac{\sin\theta_{air}}{\sin\theta_{plastic}}=1.0\cdot\frac{\sin\theta_{air}}{\sin\theta_{plastic}}$