Exam-style question
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How does the refractive index affect total internal reflection in optical fibres?.
- A.A higher refractive index increases the critical angle.
- B.A lower refractive index decreases the critical angle.
- C.Total internal reflection occurs only if the refractive index is equal.
- D.A higher refractive index decreases the critical angle.
Model answer
What a good answer should say
- A lower refractive index decreases the critical angle.
Explanation
Why this works
The critical angle is inversely related to the refractive index of the medium. A lower refractive index means a smaller critical angle, making it easier for total internal reflection to occur.
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