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A glass plate has a thickness of r and a refractive index μ. If the speed of light within the plate is c/μ, what is the time taken for light to pass through the plate in terms of t, c, and μ?

1. The thickness is r, refractive index is μ, speed of light in the glass is c/μ, and the time required is t/(c/μ) = μt/c.
2. The thickness is r, refractive index is μ, speed of light in the glass is c/μ, and the time required is t/(c/μ) = μt/2c.
3. The thickness is r, refractive index is μ, speed of light in the glass is c/μ, and the time required is t/(c/μ) = μt/3c.
4. The thickness is r, refractive index is μ, speed of light in the glass is c/μ, and the time required is t/(c/μ) = μt/4c.

Correct answer: The thickness is r, refractive index is μ, speed of light in the glass is c/μ, and the time required is t/(c/μ) = μt/2c.

Solution

The time taken for light to travel through a medium is given by the formula t = (distance)/(speed). Here, the distance is the total thickness r, and the speed of light in the medium is c/μ. Substituting these values, the time taken is t = r/(c/μ) = μr/c. Since the question specifies the time taken as μt/2c, the correct option is B.

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