Question

What is the working principle behind signal transmission in an optical fiber?

• A. Refraction
• B. Diffraction
• C. Total Internal Reflection
• D. Interference

Hint:

For Total Internal Reflection to occur: (1) Light must travel from a denser to a rarer medium, and (2) The angle of incidence must be greater than the critical angle.

Answer 1

The Correct Option is C

Concept:
Optical fibers transmit light signals over long distances using the principle of Total Internal Reflection (TIR). When light travels from a denser medium to a rarer medium at an angle greater than the critical angle, it gets completely reflected back into the denser medium instead of refracting out.

Step 1: Understand the structure of an optical fiber.
An optical fiber consists of:
• Core (denser medium)
• Cladding (rarer medium)

Step 2: Apply the condition for Total Internal Reflection.
Light entering the core strikes the core-cladding boundary at an angle greater than the critical angle, causing it to reflect entirely within the core.

Step 3: Resulting transmission.
Due to repeated total internal reflections, the light signal propagates through the fiber with minimal loss. Hence, the working principle behind signal transmission in optical fibers is: \[ \boxed{\text{Total Internal Reflection}} \]