Mastering Physics Solutions: Wavelength, Frequency, and the Speed of Light in Different Media

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

Part A = 15/f

Solution Below:

A beam of light from a monochromatic laser shines into a piece of glass. The glass has thickness L and index of refraction n = 1.5. The wavelength of the laser light in vacuum is L/10 and its frequency is f. In this problem, neither the constant nor its numerical value should appear in any of your answers.

Part A

How long does it take for a short pulse of light to travel from one end of the glass to the other?
Express your answer in terms of the frequency, f. Use the numeric value given for n in the
introduction.

The speed of light, c, equals the wavelength times the frequency:

c = (L/10) * f

And the time is just the distance divided by speed:

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

Since the index of refraction in the medium is 1.5, the wavelength will be lowered by a factor of 1.5 (L / 15) instead of (L / 10)

So:

t = L / ((L/15) * f)
t = 15 / f

15/f

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