Optical Fibres
1 mark · NormalWhich of the following is a correct statement about total internal reflection in an optical fibre?
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Correct option: It keeps light inside the core of the fibre if the angle is greater than the critical angle.
Common mistakes: Confusing which direction of refractive index total internal reflection occurs
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Marking points
A1 · 1 mark · Correct option selected: total internal reflection keeps light inside the fibre if the angle is greater than the critical angle.
Worked solution
Total internal reflection keeps light inside the core of the fibre if the angle at the boundary is greater than the critical angle. This is option 3.