Is the speed of light the same in any material?

Answer 1

The speed of light (c) in a vacuum, is exactly299,792,458 meters per second (ms-1), which rounds up very nicely to 300,000,000 ms-1, which scientists write as 3 x 108 ms-1.

In more dense media the speed is slower,

e.g. # Air, only slightly less than c, speed is 0.9997 of c. # water 0.75 of c. # fused quartz 0.686 of c. # crown glass* 0.658 of c. # dense flint glass* 0.60 of c. # diamond, approx 0.41 of c. CALCULATIONS The speed of light, using a very close approximation for calculation purposes, is taken as 3.0 x 108 m/s (metres per second). i.e. 300,000,000 m/s The greater the refractive index of the medium, the slower the speed of light in that medium/material. The speed of light in a vacuum [c] divided by the velocity of light in the material [v] equals the refractive index [n] of the material. Examples 1. calculate the refractive index of space: c/c equals 1 2. water (the speed of light in water is 225,056,264 m/s): c/ 225056264 equals 1.333 Inversely, if we know the refractive index of a material, we can calculate the velocity of light through that material, i.e. the speed of light [c] divided by the refractive index [n] equals the velocity of light [v] in that material Using the example of water, refractive index 1.333 :- 300,000,000 [c] divided by 1.333 [n] equals 225,056,264 [n] i.e. the velocity of light in water is 225,056,264 m/s. This is 225,056,264/300,000,000 ths the speed of light, or 0.75 of c. SOME REFRACTIVE INDICES * vacuum1.00 * air 1.0003 * water 1.333 * fused quartz 1.4585 * plexiglass 1.51 * crown glass* 1.52 * diamond 2.417 * gallium phosphide 3.50 *Crown glass is a type of glass used in lenses, and has a lower refractive index than flint glass which is also used in lenses. For more information, see Related Links below this box

Answer 2

No, the speed of light changes when passing through different materials. This change is due to the interaction of light with the atoms and molecules in the material, which can slow down light as it travels through substances such as water, glass, or diamond.

Answer 3

no, the speed of light in a material is always less than c because the photons are continuously being absorbed and reemitted by the material. this process takes time and slows down the light rays. the refractive index measures how much less.

Answer 4

The speed of light is only constant in a vacuum. It changes for different materials.

Light's speed in vacuum is 300 000 000 m\s.

3 x 108 m\s in air,

2.26 x 108 m\s in water

and 1.97 x 108 m\s in glass.

Answer 5

It depends on refractive index which is =( sine of angle of incidence)/(sine of angle of refraction)

And angle of refraction depends on type of material, so in a way YES, it depends on type of material.

The speed of light is only several m/s in supercooled liquid helium.

Answer 6

No, in most media it is less than the speed of light in a vacuum. Some cases have been found where the speed of light in certain media is MORE than the speed of light in a vacuum; but apparently there is reason to believe that this can't be used to transfer information faster than the speed of light; in other words, somehow this is an apparent velocity. Materials with a negative velocity have also been found - the light gets out of the material before it comes in. Again, this seems to be only an apparent speed, not usable for transferring information to the past.

Answer 7

• space, the speed of light is c or exactly 299792458 m/s
• water, the speed of light is 0.769c or 230540400 m/s
• diamond, the speed of light is 0.417c or 125013455 m/s

Answer 8

The speed of light is 2,99,7,92,458 meters per second or approximately 3x108 m/s

Answer 9

299,792,458 meters per second

186,282 miles per second

Usually designated as ' C ' in Physics formulas.

Answer 10

The speed is constant while it's in the material. It changes

at the boundary between one material and another one.