Question

Miguel is skipping rocks across the surface of a lake. After he throws it, each stone goes through the following motions:

the stone moves toward the water
the stone hits the surface of the water and bounces off
gravity pulls the stone back toward the water
the stone enters the water and slows down

In which part of the stone's movement is the stone most like a beam of light that is being refracted?

Answer 1

So waves can undergo many changes when they encounter new mediums. Two of the common ones are refraction and reflection. Reflection can be thought of like a mirror, in which the beams/waves of light will turn around completely and bounce back at the same angle:

Refraction on the other hand is when the wave still passes through the surface of the medium, but because of the properties of the medium, the wave changes direction slightly.

This is because the speed of light through a medium varies depending on the medium.
Light travels the fastest through a vacuum and slower through other mediums like water, glass, plastic etc. The relative speeds are noted by a materials index of refraction. The larger the number, the slower light moves through that medium.

But I suppose that's getting a bit off topic.
Anyways, in refraction, the wave changes direction slightly because it slows down or speeds up, depending on what medium it is changing into. Thats the same reason that light bends when it goes through water

note how the light wave changes speed and therefore direction.

Hopefully thats enough to help you figure it out :)

Good luck