3 ms·
When people colloquially say "speed of light" it understood to mean the speed of light in a vacuum. Light travels slower the higher the refractive index of the
by dagw 8y ago
When people colloquially say "speed of light" it understood to mean the speed of light in a vacuum. Light travels slower the higher the refractive index of the medium its travelling through. Saying "nearly the speed of light" indicates that the light is travelling through a medium with a refractive index very close to 1.
- raviolo 8y agoTo say that light travels at “nearly the speed of light” in any medium is a bad choice of words. Also with refraction coefficient of 1.40 - 1.45 in fiber, the term “nearly” is not appropriate if the intention was to compare with vacuum.