In everyday conditions, light moves at 299,792,458 meters per second in a vacuum, and its speed decreases slightly when ...

Save guides, add subjects and pick up where you left off with your BBC account. The speed of light is determined by the medium (material) through which the light is travelling. Light travels ...

The change in direction of a ray depends on the change in the speed of the light and can be used to calculate the refractive index. For the example above the refractive index \(n\) of the glass is ...