Question

What is the working principal of optical fiber? (A) Refraction (B) Total internal reflection (C) Dispersion (D) Scattering

Short answer

The working principle of optical fiber is \( \textbf{(B) Total Internal Reflection} \). Total internal reflection occurs when a light wave traveling in a medium with a higher refractive index strikes the boundary with a medium of lower refractive index at an angle greater than the critical angle, causing the light wave to be completely reflected back into the higher refractive index medium. This enables the transmission of light signals over long distances with minimal signal loss.

Step-by-step solution

Understanding Optical Fiber

Optical fiber is a flexible, transparent fiber made of glass or plastic that can transmit light signals over long distances with minimal loss. These fibers are commonly used in telecommunications, internet services, and other data-oriented applications.

Discussing Refraction

Refraction is the change in direction of a light wave when it passes from one medium to another with different refractive indices. Although refraction plays a crucial role in the transmission of light through the fiber, it is not the main working principle behind optical fibers.

Discussing Total Internal Reflection

Total internal reflection occurs when a light wave traveling in a medium with a higher refractive index strikes the boundary with a medium of lower refractive index at an angle greater than the critical angle. This causes the light wave to be completely reflected back into the higher refractive index medium with no light escaping into the lower refractive index medium. This is the principle that allows optical fibers to transmit light signals over long distances with minimal loss.

Discussing Dispersion

Dispersion refers to the spreading of light signals as they travel through a medium due to different wavelengths traveling at different speeds. Dispersion can lead to signal distortion in optical fibers. Although dispersion is an important factor to consider and manage in fiber-optic systems, it is not the working principle of optical fibers.

Discussing Scattering

Scattering is the process by which light waves interact with particles in a medium and are reflected or deflected in various directions. Scattering can result in signal loss in optical fibers; however, it is not the working principle of optical fibers.

Identifying the Correct Answer

Based on the analysis of each option, the working principle of optical fiber is (B) Total Internal Reflection. This is because it enables the transmission of light signals over long distances with minimal signal loss.