Speed of light in vacuum is:
The speed of light is measured to have the same value of c = 3x108 m/s no matter who measures it.
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 ?
Light is refracted when it crosses the interface from air into glass in which it moves more slowly. Since the light speed changes at the interface, the wavelength of the light must change, too. The wavelength decreases as the light enters the medium and the light wave changes direction.
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.