## Distance a wave travels?

How far will a 1300 nanometer wave travel in 100 nanoseconds?

I know its simple but I can't remember how to do it...
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 Recognitions: Gold Member It all depends on how fast this wave is going. Since you're considering an atomic scale wave, I'm guessing you're asking about light? How fast does light travel?
 Yeah its a laser... 1.44 refraction index

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Gold Member

## Distance a wave travels?

Okay you need to give the full description of the problem first, we can't guess at what the situation is.
 Ok sorry. Is that enough information?
 what is "refraction index" :-s?
 Recognitions: Gold Member Science Advisor Staff Emeritus Are you saying that you are talking about light traveling for 100 nanoseconds in a medium with refractive index of "1.44"? The refractive index, of some medium through which light can travel, is defined as the ratio of the speed of light in vacuum to its speed in the medium. Here, you are saying that $$\frac{c}{v}= 1.44$$ so that $$v= \frac{c}{1.44}= .6944 c$$
 If this is so,are the problem necessary to know wavelength? because we knowed v=c/1.44
 So I guess wavelength is irrelevant? We know velocity and time, so I guess the wavelength never mattered in the first place...