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
The speed of light is slower in water and glass compared to its speed in a vacuum, but faster in diamond. This difference is due to the different optical properties of these materials, which affect how light propagates through them. In water and glass, light travels at about 3/4 of its speed in a vacuum, while in diamond, light travels even faster than in a vacuum.
Light travels at a slower speed in glass compared to vacuum. The ratio of the speed of light in vacuum to the speed of light in glass is called the refractive index of glass. So, the distance light travels in glass would be the distance it travels in vacuum divided by the refractive index of glass.
it travels at c (speed of light in a vacuum)
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 .
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 any medium is slower than in a vacuum. In light flint, the speed of light is approximately 60% of its speed in a vacuum, which is about 183,600 miles per second.
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.
Light changes speed when it moves from glass to air due to the difference in optical density between the two mediums. In glass, light travels slower due to the higher density, resulting in refraction as it enters the less dense air. This change in speed causes the light to bend and change direction.