# Wavelength, Frequency, and Speed of Light in Different Media

1. Homework Statement
A beam of light from a monochromatic laser shines into a piece of glass. The glass has a thickness L and an index of refraction n . The wavelength of the laser light in vacuum is L/10 and its frequency is f. In this problem, the constant should not appear in any of your answers.

How long does it take for a short pulse of the light to travel from one end of the glass to the other?

2. Homework Equations

None of any significance i can think of that will help us here

3. The Attempt at a Solution

t = (L/10)(f)(n)

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Okay, the best thing to do is to draw a diagram, I always find this helps to visualize the
problem. You know that the time the light is inside the media is simply t = s/v. Now s = L
so t = L/v. And the speed of the light inside the glass is of course c/n. Hence t = Ln/c. I wasn't sure what you meant by "the constant should not appear in any of your answers" if you mean that the frequency of the light, which is constant whatever media it is in, then that's your answer. Otherwise, you can simply substitute to get the answer in the form that you need.
You can also use c = l*f (l=wavelength, f=frequency) will also be of use.

Matt.

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