Compared with the speed of visible light in a vacuum (or in space),the speed of visible light in water or in glass is:
A) faster.
B) slower.
C) exactly the same because the speed of light cannot vary.
D) much faster.

Question

Quizplus · Accepted Answer

The speed of visible light in water or glass is slower than it is in a vacuum or in space. This is due to the higher refractive index of these materials compared to air or vacuum, which causes the light to bend and travel at a slower rate.

Compared with the Speed of Visible Light in a Vacuum