Question

Why does light refract when it goes through a prism? How does the glass bend the light rays?

Answer 1

The glass slows down the light waves as they enter the new medium at an angle

Explanation:

If the light ray entered the glass at a `90^o` angle there would be no refraction as all of the light would be slowed at the same time.

When the light ray enters the glass at an angle the leading edge of the ray that enters the medium first slows down while the rest of the ray slows down later, This causes the light to refract or bend.

Think of it as a car hitting a deep puddle. If both wheels hit the puddle at the same time the car slows down but does not turn.
If the only the right wheel hits the puddle, the right wheel slows down while the left wheel continues at the same speed. This well cause the car to make a sharp turn to the right as the wheels are connected.