Optical Fibres
3 marks · EasyAn engineer uses optical fibres to inspect the inside of a jet engine.
State two reasons why using an optical fibre is useful in this situation.
Explain how light travels from the entrance to the exit of the fibre.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) — · must show Can reach hard-to-access places, Transmits image/light around bends
(b) By total internal reflection in the core · must show Mentions total internal reflection
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Marking points
B1 (a) · 1 mark · States one advantage: e.g. can inspect places that cannot be accessed directly
B2 (a) · 1 mark · States a second valid reason: e.g. light travels through bends
B3 (b) · 1 mark · Explains that light travels by total internal reflection
Worked solution
- (a) Optical fibres can carry light around bends to see inside tight spaces and can reach places engineers cannot see directly.
- (b) Light reflects repeatedly inside the fibre by total internal reflection so it reaches the end.