Question

Total internal reflection in optical fibers occurs when:

• A. Light goes from low to high refractive index
• B. Angle of incidence \(<\) critical angle
• C. Light is absorbed by the cladding
• D. Angle of incidence \(>\) critical angle and \( n_1>n_2 \)

Hint:

Total internal reflection occurs when light is traveling from a higher refractive index medium to a lower refractive index medium with an incidence angle greater than the critical angle.

Answer 1

The Correct Option is D

Total internal reflection in optical fibers occurs when light is traveling from a medium with a higher refractive index to one with a lower refractive index. For total internal reflection to happen:
1. The angle of incidence must be greater than the critical angle.
2. The refractive index of the core (\( n_1 \)) must be greater than the refractive index of the cladding (\( n_2 \)).
The critical angle is the minimum angle of incidence at the interface between two media that results in total internal reflection. If the angle of incidence exceeds this critical angle, light will be completely reflected inside the core, ensuring that the signal remains within the optical fiber.
Therefore, the correct condition for total internal reflection is when the angle of incidence is greater than the critical angle, and the refractive index of the core is greater than that of the cladding.