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JAMB Physics 1984 Question 32

Question 32

Refraction of Light

A coin is placed at the bottom of a cube of glass t cm thick. If the refractive index of the glass is μ, how high does the coin appear to be raised to an observer looking perpendicularly into the glass?

  1. A.1/(t − μ)
  2. B.t(μ − 1)/μ
  3. C.t(1 + 1/μ)
  4. D.−
  5. E.μt.
Show the answer and explanation

Answer: B (t(μ − 1)/μ)

Explanation

Apparent depth = t/μ, so the coin seems raised by t − t/μ = t(μ − 1)/μ.