Question

When a wave hits a boundary, what determines how much is reflected and refracted?

Answer 1

Answer:

Angle and speed of wave

Explanation:

The two phenomena involved here are:

- Reflection: reflection occurs when a light wave bounces off the interface between two mediums, returning into the first medium, at a different angle

- Refraction: refraction occurs when a light wave passes through the interface between the two mediums, passing into the second medium, changing direction and speed

The coefficient of reflection tells what is the fraction of the wave that is reflected over the total; it is calculated as

$R=|\frac{n_1 cos \theta_1 - n_2 cos \theta_2}{n_1 cos \theta_1 + n_2 cos \theta_2}|^2$

where

$n_1, n_2$ are the index of refraction of the 1st and 2nd medium

$\theta_1, \theta_2$ are the angle between the ray of light  and the normal to the interface in the 1st and 2nd medium

From the formula, we see that the % of wave that is reflected depends on the angle and the index of refraction. Moreover, the index of refraction is related to the speed of the wave by:

$n=\frac{c}{v}$

where c is the speed of light in a vacuum and v the speed of light in the medium; therefore, the correct answer is

Angle and speed of wave