A light ray travels from a transparent medium with refractive index into air (). What is the critical angle for total internal reflection?
Answer and explanation
Correct answer: B.
- Step 1: Recall Snell's law at the critical boundary where angle of refraction is : .
- Step 2: Substitute indices: .
- Step 3: Calculate inverse sine: .
Answer
41.8 degrees.
Why not the others: '' is the critical angle for water (); '' corresponds to ; '' corresponds to .
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