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.
About 2/3 its speed in a vacuum.
3/4th
They are equal.
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 .
Those speeds are equal, even though the speed of the light was temporarily less while it was inside the glass.
About 2/3 its speed in a vacuum.
3/4th
Depends on the refractive index of the medium itself
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 is minimum in Glass. It is because light travels at minimum speed in solids.
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.
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.
They are equal.
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 .
Those speeds are equal, even though the speed of the light was temporarily less while it was inside the glass.
Light's apparent speed is fastest definitely in a vacuum and slower in water or glass. Light in air behaves more like in a vacuum than in water or glass.