Question

How does light bend if it is going from an object with a higher density through an object with a lower density?

Answer 1

Snell's law relates the indices of refraction for two media with their angles of refraction with respect to the normal, and states:

`n_1sintheta_1 = n_2sintheta_2`

where:

• `n_i` is the index of refraction of medium `i`.
• `theta_i` is the angle of refraction (with respect to the normal of the boundary line) in medium `i`.

A denser medium has a higher index of refraction.

Let `n_2 < n_1`, so that we go from a higher-density medium to a lower-density medium. Then, since `n_i prop 1/sintheta_i`, or `n_i prop sintheta_j` (`i ne j`), we must have that `sintheta_2 > sintheta_1`.

Therefore, `color(blue)(theta_2 > theta_1)`, and light bends farther away from the line normal to the boundary between the two media, as shown by the reverse of the light ray below: