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 c nor its numerical value should appear in any of your answers. (1)How long does it take for a short pulse of light to travel from one end of the glass to the other?

15/f s

Explanation:

The refractive index n = 1.5 of the glass is n = λ₁/λ₂ where λ₁ = wavelength of monochromatic light in vacuum = L/10 and λ₂ = wavelength of monochromatic laser in glass.

So, λ₂ = λ₁/n.

We know the speed of light in glass, v = fλ₂ and λ₂ = v/f.

The light covers a distance d = L in time, t = d/v (since v = d/t)

So, the time it takes the pulse of light to travel from one end of the glass to the other is t = d/v = L/fλ₂ = L/fλ₁/n = nL/fλ₁ = nL/fL/10 = 10 × 1.5/f = 15/f s

So, the time it takes the pulse of light to travel from one end of the glass to the other is t = 15/f s

a and b sometimes have a positive value