What does light waves do when it moves from one medium to another?

Answer 1

A light wave can slow down or speed up when it enters another medium.

Since the speed of wave motion in general depends on characteristics of the environment,

you can always expect the speed of a wave to change as it moves from one medium to

another. In the case of sound, it's the mechanical characteristics that matter, whereas

for light and other electromagnetic waves, the determining characteristics are the

electrical ones.

So the speed of light changes when it enters a different medium. Now, since the product

of (frequency) x (wavelength) is the wave speed, and the frequency can't change, we

notice that if the speed changes, then the wavelength also changes in a new medium.

Furthermore, right at the interface ... the boundary between the two media ... if the

light doesn't hit the boundary exactly perpendicular to it, then we say that the light

is "refracted" at the boundary, meaning that the light leaves the boundary in the

new medium in a different direction compared to its direction in the previous medium.