The speed of light is greatest in vacuum, and somewhat less in any material medium.
The exact number depends on the individual material. They're all different.
About 2/3 its speed in a vacuum.
The speed of light is minimum in Glass. It is because light travels at minimum speed in solids.
glass
In glass, light will go somewhat slower than in a vacuum. Air is almost like a vacuum, with respect to the speed of light - some difference still exists, though.In glass, light will go somewhat slower than in a vacuum. Air is almost like a vacuum, with respect to the speed of light - some difference still exists, though.In glass, light will go somewhat slower than in a vacuum. Air is almost like a vacuum, with respect to the speed of light - some difference still exists, though.In glass, light will go somewhat slower than in a vacuum. Air is almost like a vacuum, with respect to the speed of light - some difference still exists, though.
There are several different types of glass, and light has a somewhat different speed in each of them. On the average, the speed of light across all typical types of glass is in the neighborhood of 2/3 its speed in vacuum, or around 200,000 km/sec .
it travels at c (speed of light in a vacuum)
3/4th
It will depend on the type of glass, and something called its refractive index. All materials have a refractive index which will effect the speed of the light through it. The speed of light through a vacuum is 3.0x10^8 m/s, and a material such as glass will be lower than this.
The speed of light IN A VACUUM is always the same. In substances other than the vacuum, the speed of light is usually slower than in a vacuum.
Speed of light in vacuum = ' c '-- Speed of light in Air . . 99.97% of ' c '.-- in Water . . . . . . . . 75% of ' c '.-- in Crown Glass . . . 64.9%-- in Flint Glass . . . . . 61.7%-- in Diamond . . . . . . 41.3%
The speed of light in glass is the reciprocal of the refractive index of the glass or 1/(refractive index). Not all glass is the same: its refractive index can range from less than 1.5 for Pyrex (a borosilicate glass) to more than 1.9 for (impure) flint glass. This means the speed of light in glass can range between 0.52 and 0.68 of its speed in vacuum.
The velocity of light is greatest when travelling through a vacuum. When travelling through something else, a glass material say, then its velocity is slower. The refractive index is the ratio of the speed of light in a vacuum to the speed of light in that substance. For example light travels in a vacuum about 1.3 times as fast as in water, so we say water has a refractive index of 1.3. And it is likely that the velocity in the glass will be different at different wavelengths of light.