3/4th
About 2/3 its speed in a vacuum.
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.
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 .
In vacuum, the speed of light is a constant c = 300 000 000 m/s. In a transparent medium, light slows down by a factor of 1/n where n is called the refractive index of the medium. The refractive index of most common glasses is around 1.5 (3/2), so light will travel at a speed v = c/n = (2/3)c = 200 000 000 m/s in the glass.
The speed of light in vacuum is 299,792,458 meters per second, and that's not an average. That's what it always is.
About 2/3 its speed in a vacuum.
Depends on the refractive index of the medium itself
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.
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 .
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%
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.
light in a vacuum
No, slower.
No
No
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.