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Q & A: Is the speed of light a function of frequency or wavelength?

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Most recent answer: 04/01/2013
Q:
Can we change the speed of light in a vacumm by changing its wavelength or frequency?? I think it is not possible but I need a reasonable answer.
- Pranjal` (age 15)
India
A:
In a perfect vacuum the answer is no.    All laboratory experiments and astronomical observations have confirmed this.   However, in a medium that has an index of refraction the answer is different.  As you probably know the speed of light in a refractive medium is v = c/n where n is the index of refraction.   Now n can be, and usually is, a function of the wavelength of the light.   So in that case, the answer is yes.

LeeH

(published on 04/01/2013)

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