Exam-style question
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A ray of light passes from air into glass with a refractive index of 1.5. What is the critical angle for total internal reflection?.
- A.41.8°
- B.48.6°
- C.60.0°
- D.30.0°
Model answer
What a good answer should say
- 41.8°
Explanation
Why this works
The critical angle can be calculated using the formula: critical angle = sin⁻¹(1/n), where n is the refractive index. Substituting gives: sin⁻¹(1/1.5) = 41.8°.
This angle is where light cannot pass into the second medium and is reflected instead.
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