Is the speed of light slower in glass or water?

Question

Justify your answers please.

Answer 1

Glass. I have read it some where that sound travels fastest in solid, then liquid and slowest, air. So I think should be the same for light. There is a website good for physics. You can try it out.

Answer 2

At the risk of sounding like a pedant the speed of light is a constant. It will be refracted differently as it travels through different substances. Thickness, tint, clarity etc of the glass would contribute as would purity of the water etc. At a guess Im going to say water.

I would be interested to know if it got through salt or fresh water faster.

Answer 3

Glass because it's index of refraction varies usually between 1.52 and 1.56, Whereas water has an index of refraction of 1.333. Because glass has a higher index of refraction, it means that it is a more dense medium than water. Thus, this is why light travels more slowly in glass than in water.

Answer 4

Glass.

Answer 5

it depends on how thick the glass is

Answer 6

glass

Answer 7

the refractive index of a sustance if what determines the speed of light in that medium...

here's one way of calc. it

(absolute r.i.)=speed of light in medium/speed of light in vaccum

(relative r.i.)=speed of light in medium 1/speed of light in medium 2

r.i. is denoted by 'mu'

anyway...

the r.i. of water is less than the refractive index of glass [im saying the average r.i., crown glass and flint glass have different r.i.'s]

substitute in the formula and you'll see that the speed of light in glass is much less than the speed of light in water...

Answer 8

glass, because the more closely packed the atoms of an object are, the harder it is for light to pass through it.  thus, light travels slower through glass, which is more solid, than water.

Answer 9

Yes, it is. The speed of light is slower in any transparent material medium than it is in a vacuum (3 x 10^8 m/s). I don't know how to justify the statement; it's just something I remember learning in high school.

P.S. Having read some of the other answers, I realise I probably misunderstood the question. I thought you meant 'Is it slower in glass or water than it is in a vacuum?'

The speed of light is not a constant. When people say that it is a constant, they mean in a vacuum.