You need to implement a network cabling medium that is not susceptible to electromagnetic interference (EMI). Which type of cable should you choose?

Introduction / Context:
Electromagnetic interference (EMI) and radio frequency interference (RFI) can degrade the performance of copper based network cabling, especially in environments with strong electrical noise such as factories or near heavy machinery. Choosing the right cabling medium can significantly improve signal integrity. Fiber optic cabling is well known for its immunity to EMI because it uses light rather than electrical signals.

Given Data / Assumptions:

The environment where the network will be deployed has significant EMI or the risk of such interference.
The goal is to choose a medium that is inherently immune to EMI, not just resistant.
Options include common copper based cables and fiber optic cable.

Concept / Approach:
Copper based cabling (coaxial and twisted pair) carries electrical signals and therefore can be affected by external electromagnetic fields. While shielding and twisted pairs can reduce susceptibility, they cannot completely eliminate it. Fiber optic cable uses strands of glass or plastic to transmit light pulses; since there is no electrical signal traveling through metal conductors, fiber is immune to EMI and RFI. This makes it the best choice for noisy environments or long distance high speed links.

Step-by-Step Solution:
Evaluate coaxial cables (thicknet and thinnet): both are copper based and carry electrical signals, so they can be affected by EMI, despite some shielding. Consider unshielded twisted pair (UTP) cables such as Category 5 and Category 3: twisting reduces interference, but the cables are still copper and not immune to strong EMI. Recognize that fiber optic cables transmit data as light, not electricity, and therefore are immune to electromagnetic interference. Among the options given, only fiber optic cable fully meets the requirement of not being susceptible to EMI. Thus, the correct choice is fiber optic cabling.

Verification / Alternative check:
Network design guides often recommend fiber optic cabling for industrial environments, areas near high voltage equipment and for long distance runs, precisely because it is immune to EMI and offers high bandwidth. This consistent recommendation across industry sources confirms that fiber is the right answer when EMI immunity is the primary concern.

Why Other Options Are Wrong:
Option a (thicknet coax) and option b (thinnet coax) both use copper conductors and are susceptible to EMI, even though coaxial design offers some shielding.
Option c (Category 5 UTP) and option e (Category 3 UTP) use unshielded twisted pair, which reduces but does not eliminate interference; they are not immune to EMI.
Only fiber optic cable avoids EMI entirely because it carries light signals through non metallic conductors.

Common Pitfalls:
A pitfall is to think that any shielded or twisted copper cable is completely immune to interference. In reality, strong electromagnetic fields can still induce noise in copper conductors. Another confusion arises between EMI immunity and lightning or surge immunity; while fiber is excellent for EMI, physical installation practices must still consider other hazards.

Final Answer:
To avoid EMI, you should use fiber-optic cable as the network medium.