Question

In optical fibers, does the core or the cladding have a higher refractive index?

• A. Core
• B. Cladding
• C. Both are equal
• D. It varies randomly

Hint:

Optical fiber principle → Total internal reflection
Core refractive index > Cladding refractive index

Answer 1

The Correct Option is A

Understanding the Question: The question asks to compare the refractive indices of the two layers of an optical fiber.
Key Formulas and approach: Optical fibers rely on Total Internal Reflection (TIR). For TIR to occur, light must travel from a medium with a higher refractive index ($n_1$) toward a medium with a lower refractive index ($n_2$).
Detailed Solution:
Step 1: The Goal. Light must stay trapped inside the center (the core) to transmit information.
Step 2: Applying Physics. To reflect light back into the core at the boundary, the outer layer (cladding) must be "thinner" optically.
Step 3: Relation. This means the refractive index of the core ($n_{core}$) must be greater than the refractive index of the cladding ($n_{clad}$).
Conclusion: The core has a higher refractive index.