NEET Physics: Optical Fibers questions with solutions

Q1. Assertion Optical fibres are used to transmit light without any appreciable loss in its intensity over distance of several kilometers. Reason Optical fibres are very thick and all the light is passed through it without any loss.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Answer: Assertion is correct but Reason is incorrect

Optical fibres guide light by repeated total internal reflection, so the signal can travel kilometers with very little loss. The reason is wrong because fibres are not thick, and some loss still occurs; the low loss is due to their optical design, not because all light passes through perfectly.