Optical fibre are used for long distance communication because

Options

A. it amplifies signals to be transmitted
B. it transfer signals faster than electrical cables
C. it pre-emphasise weak signals
D. it provide little attenuation as compared to electrical cable for light propagation

Answer

### Step-by-Step Solution:

1. **Understanding Optical Fibers**:
Optical fibers are thin strands of glass or plastic that transmit light signals over long distances. They are designed to carry data in the form of light pulses.

2. **Signal Amplification**:
One of the key advantages of optical fibers is their ability to amplify signals. This means that the strength of the signal can be increased, allowing it to travel longer distances without losing quality.

3. **Speed of Transmission**:
Optical fibers transfer signals at a much faster rate than traditional electrical cables. This is due to the speed of light being significantly faster than the speed of electrical signals in copper wires.

4. **Pre-emphasis of Weak Signals**:
Optical fibers can pre-emphasize weak signals, which helps in maintaining the integrity of the data being transmitted. This ensures that even if the signal starts weak, it can be boosted effectively during transmission.

5. **Low Attenuation**:
Attenuation refers to the reduction in signal strength as it travels through a medium. Optical fibers have very low attenuation compared to electrical cables, meaning that the light signals can travel longer distances without significant loss of strength.

6. **Electromagnetic Interference (EMI)**:
Unlike electrical cables, optical fibers are not susceptible to electromagnetic interference. This makes them more reliable for long-distance communication, as external electrical noise does not affect the light signals.

7. **Total Internal Reflection**:
The principle of total internal reflection is crucial in optical fibers. When light travels through the fiber, it reflects off the walls of the fiber, allowing it to travel long distances without escaping. This is facilitated by the critical angle of incidence.

8. **Conclusion**:
Due to these advantages—signal amplification, high transmission speed, low attenuation, and immunity to electromagnetic interference—optical fibers are preferred for long-distance communication.