Speed of light in vacuum is:
The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. It's exact value is defined as 299 792 458 metres per second ( or approximately, 3*108 m/s)
When light travels from air to glass separated by sharp boundary
When light travel in air it is easy for light to travel easily in air because there are many few restriction but when it enters in glass it have to face a lot of restrictions and its speed is reduced so it bands towards normal.
What will happen when a ray enters from glass to air medium ?
When a ray of light passes from a less dense material into denser material it is bent away from the surface between the two materials. This means that in this situation the angle of refraction is always less than the angle of incidence.
The speed of light in glass is 1.5 x 108m/s. Then refractive index of glass is
Light travels faster in substance X as compared to substance Y, then refractive index is greater for
As the refractive index increases, the velocity of light decreases.