Final answer:
Signal loss in a link is measured as a percentage of power loss, with one-fourth of a percent (0.25%) being an acceptable standard. Lower voltages require higher current, leading to more loss, and superconducting lines could potentially reduce this loss to zero.
Step-by-step explanation:
The value commonly used to describe signal loss in a link is the percentage of power loss. For efficient power transmission, only a small fraction of power loss, such as one-fourth of a percent (0.25%), is considered acceptable. When transmitting electrical power, if the voltage is lower, more current is needed to transmit the same amount of power. This results in higher signal loss due to the fixed resistance of the transmission lines. For instance, transmitting 100 megawatts (MW) at 25 kilovolts (kV) would require a current of 4000 amperes (A), leading to a substantial power loss of 16.0 MW, or 16.0%. To reduce this loss, one could opt for lower-resistance lines, which entails using larger and costlier wires. In a hypothetical scenario where superconducting lines could be produced economically, the loss would be eliminated.