Does blue light travel slower than violet light? If so, why?

Question

I heard that blue light is the slowest source of light(according to my physics text book). I think that the a ray of violet light should travel slower than a ray of blue light.

Answer 1

Your question: "Does blue light travel slower than violet light? If so, why? I heard that blue light is the slowest source of light(according to my physics text book). I think that the a ray of violet light should travel slower than a ray of blue light."



So you hear your book talking to you?



I was going to suggest getting a more realistic text, but it appears the problem is much worse.



Do you see what I'm saying?

Answer 2

light only varies in speed as a function of frequency when passing through a medium (light speed is the same for all frequencies in a pure vacuum). Generally speaking, the higher the frequency, the more that the speed is reduced by the medium. this is why "blue" light bends more than "red" light when entering a substance (why light will separate into a spectrum after passing through an interface).



But your quibble is correct, "violet" light will normally slow more than "blue" light. Typically speaking, though, the visible light spectrum is discussed in terms of the high frequency ("blue") end versus the low frequency ("red") end. we consider violet light as part of the blue end.

Answer 3

In a vacuum all colours of light travel at the same speed.



But in most (pehaps all) transparent materials like glass, violet is the slowest.



It is common to refer to the ends of the visible spectrum as:

- the red end and

- the blue end.

But the blue end should really be called the violet end!



This is done because the blue/indigo/violet range is perceived by the eye as generally blue-ish; probably because the eye is more sensitive to blue than to indigo and violet.



My old physics teacher taught us:

"blue bends best"

as a way to remember which colours bend most in a prism. It is incorrect but is easier to remember than the technically correct 'violet bends best" or "red bends least".

Answer 4

I do not know where you read such a thing. The velocity of any light wave depends on the property of the medium.Some media may be faster for the blue rays than red rays ot other way round.



You must know the refractive index of the medium for that ray.

Answer 5

Nonsense - the speed of light is the speed of light. No matter what the frequency (colour) it is all the same speed.