NEETPhysicsRay Optics
Assertion (A) Propagation of light through an optical fibre is due to total internal reflection taking place at the core-clad interface. Reason (R) Refractive index of the material of the core of the optical fibre is greater than that of air.
Options
- Aboth (A) and (R) are true and (R) is the correct explanation of (A)
- Bboth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
B. both (A) and (R) are true but (R) is not the correct explanation of (A)
Step-by-step solution
Assertion and Reason Analysis - Assertion (A): The assertion states that light propagation through an optical fiber is due to total internal reflection (TIR) at the core-clad interface. This is true. Light entering the fiber's core strikes the boundary between the core and the cladding at an angle greater than the critical angle, causing the light to reflect back into the core rather than refracting out. This process repeats, allowing light to travel long distances inside the fiber. - Reason (R): The reason states