Question

• Assertion (A): Propagation of light through an optical fibre is due to total internal reflection taking place at the core-cladding interface.
• Reason (R): Refractive index of the material of the cladding of the optical fibre is greater than that of the core.

विकल्प

• If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

• If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

• If Assertion is true but Reason is false.

• If both Assertion and Reason are false.

Answer 1

If Assertion is true but Reason is false.

Explanation:

Propagation of light through an optical fibre is due to total internal reflection taking place at the core-cladding interface. The claim is correct.

One requirement for total internal reflection is that light goes from a denser to a rarer medium. Total internal reflection occurs in optical fibre as light passes from the core to the cladding. As a result, the core's refractive index should be larger than that of the cladding. As a result, the reason is untrue.