Question

The working principle of Optical Fiber Cable (OFC) is:

• A. Scattering
• B. Dispersion
• C. Total internal reflection
• D. Interference

Answer 1

Answer:

C. Total internal reflection

• Correct Answer : Total internal reflection

Optical Fiber Cable (OFC)

Working Principle

• Optical fiber cable works on the principle of Total Internal Reflection (TIR).

• Light is guided through the fiber by repeated reflections inside the core, enabling data transmission over long distances.

Total Internal Reflection

• TIR occurs when a light ray traveling in a denser medium hits the boundary with a rarer medium at an angle greater than the critical angle.

• After exceeding the critical angle, the light does not refract out; instead, it reflects back entirely into the same medium.

Why OFC Uses TIR?

• Fiber has two main parts:

  • Core: higher refractive index (e.g., n_1)

  • Cladding: lower refractive index (e.g., n_2, where n_1 > n_2)

• Since n_1 > n_2, light entering the core at suitable angles experiences total internal reflection and keeps travelling through the fiber.

Related Important Points

• The maximum angle for which light remains trapped inside the core is linked to critical angle; this leads to the concept of acceptance angle and numerical aperture (NA).

• OFC transfers data in the form of light pulses, not electrical signals directly.

• Other options like scattering, dispersion, and interference are effects/limitations in communication, but the core guiding mechanism of OFC is TIR.