What occurs to light when it moves from glass back to air?

When light transitions from glass back to air, it speeds up. This phenomenon occurs due to the difference in the refractive indices of the two mediums. Glass has a higher refractive index compared to air, meaning that light travels slower in glass than it does in air.

As light exits the denser medium (glass) and enters the less dense medium (air), the change in speed is accompanied by a change in direction, which also causes the light to bend away from the normal line. However, while bending does happen during this transition, the primary effect that accurately describes what happens to the light in this case is that it speeds up.

This change in speed and direction is governed by Snell's law, which describes how light rays change their speed and bend at the interface of different mediums. The combination of increased speed and bending when transitioning from glass to air reflects the fundamental behavior of light as it interacts with different materials.