Question

What is the equation for Snell's law?

Answer 1

where
`n_1` is the index of refraction of the first substance that light travels through
`theta_1` is the angle of incidence
`n_2` is the index of refraction of the second substance that light travels through
`theta_2` is the angle of refraction

Then you need to isolate your unknown.

Example:

Light in air (`n_1` = 1.0003) is incident upon a block of crown glass (`n_2` = 1.52) at an angle of `35.0^o`. What is the angle of refraction?

`n_1` sin `theta_1` = `n_2` sin `theta_2`
(Isolate sin `theta_2` by dividing both sides by `n_2`)
`n_1` sin `theta_1` / `n_2` = sin `theta_2`
(1.0003) (sin 35.0) / 1.52 = sin `theta_2`
0.5737 / 1.52 = sin `theta_2`
0.3775 = sin `theta_2`
(To find `theta_2`, you need to find the inverse sine of this value. On your calculator, press the 2nd function key, then the sine key.)
`22.2^o` = `theta_2`