ABSTRACT
For a given length of cable, fiber has far less signal attenuation than copper, which allows you to use longer cable runs.
A copper circuit can pick up unwanted electrical "noise" (spurious signals unrelated to the desired source signal). This noise is electrically induced into the circuit by virtue of the cable running close to AC power wires, fluorescent lights, or other noise sources. A copper circuit can also pick up stray signals from adjacent data circuits. What's more, if the circuit is close enough to be picking up outside data signals, it's also likely to be inducing its own signals into the other circuits. This problem is known as "crosstalk:'
A further disadvantage of copper data links is that they are susceptible to transient overvoltages (or impulses), which can momentarily reach hundreds or thousands of volts. Transient overvoltages can damage computers and networking equipment and, at the very least, they can be erroneously interpreted as data, leading to problems similar to those caused by electrical noise contamination.
