What is the critical angle for total internal reflection at a glass-water interface, if the refractive index of glass is and that of water is ?

Answer and explanation

Correct answer: B.

  1. Step 1: Total internal reflection occurs when light travels from an optically denser medium () to a rarer medium ().
  2. Step 2: State the critical angle condition: .
  3. Step 3: Substitute values: . Taking the arcsine: .
Answer
.
Why not the others: is the critical angle for a glass-air interface (); is the critical angle for a water-air interface (); corresponds to .

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