You're right to question that! It seems like the ray *should* change direction when entering the glass. The reason it doesn't in this scenario is that the ray is entering the glass at a right angle (90 degrees) to the surface.

Here's why:

* Refraction: When light passes from one medium to another (like air to glass), it bends. This bending is called refraction and is caused by the change in the speed of light in different materials.

* Angle of Incidence: The angle at which the light ray hits the surface is called the angle of incidence.

* Angle of Refraction: The angle at which the light ray bends as it enters the new medium is called the angle of refraction.

The key point is: When the angle of incidence is 90 degrees (meaning the light hits the surface perpendicularly), the angle of refraction is also 90 degrees. This means the light ray continues in a straight line without changing direction.

Think of it this way: Imagine you're walking straight towards a wall. If you hit the wall head-on, you don't change direction, right? Similarly, light hitting a surface at 90 degrees doesn't bend.

Let me know if you have any other questions about refraction or optics!