Question

Fibre is preferred over electrical cabling when _______ bandwidth, _______ distance or _______ to electromagnetic interference is required.
1. low, long, immunity
2. low, short, stability
3. high, long, immunity
4. high, short, stability

Answer 1

Correct Answer - Option 3 : high, long, immunity

Explanation:

Fiber-optic communication

This is the method of transferring the information from one place to another in the form of pulses of IR light through an optical fiber.

• This is the efficient technique for the faithful production of data at the receiver.
• The most commonly used transmitters are semiconductor devices such as LEDs or LASER.
• The main component of the optical receiver is the 'photo detector'.

Fiber-optics are safer

The fiber is nonconducting and is therefore safe in all electromagnetic environments. This means it can safely be used around electrical transmission lines, as well as in high RF and magnetic fields.

Fiber optics are lighter

For many combinations of power and distance, optical fiber is much lighter than any practical electrical cable.

At voltages below ~1,000 V, electrical conductors are much heavier than optical fiber for similar power delivery capacity. Conductor weight tends to scale as 1/voltage²(because power loss varies as V²/R), so even at 400 volts, copper weighs over twice as much as fiber.

Fiber optics have no RF interference, emissions, or inadvertent antenna

Optical fiber has no RFI/EMI issue because it is not a conductor.

• Copper wire, on the other hand, can leak signals and can be impacted by RFI.
• It can act as an antenna, interfering with data being sent along the cable.
• In extreme cases, copper wire can pick up energy from nearby high-power transmitters, not only interfering with data transmission but potentially overheating the wire.

Fiber optics have Higher data bandwidth

Multimode optical fiber can readily transmit high bandwidth data over long distances. 

• A typical bandwidth-distance product for multimode fiber is 500 MHz/km, so a 500 m tether can transmit 1 GHz (several Gbits/second, with appropriate modulation).
• Twisted pair optimized for high data rates (Cat 6) can transmit 500 MHz over only 100 meters (bandwidth-distance product of 50 MHz/km);

Both fiber and copper are reasonable in terms of durability

The ultra-pure silica glass used in optical fiber has a higher tensile strength than copper.

The jacketing material further strengthens and protects the fiber.

Disadvantage

The cost of the cable is higher than the electrical cables.

The below table shows the information which is preferred for the particular parameter.

Parameter	Optical Fiber	Copper wire
Safety	Preferred	No
Weight	Preferred	No
RF effects	Preferred	No
Data bandwidth	Preferred	No
Durability	Preferred	No
Cost	NO	Preferred

 

Conclusion:

Option 3 is correct.