Final answer:
Communication signals are transmitted through transmission lines using electromagnetic waves by varying the wave's amplitude, frequency, or phase. These signals travel at nearly the speed of light, and high voltages are used in long-distance power transmission to minimize losses.
Step-by-step explanation:
Communication signals in the form of high-frequency voltages are transmitted to and through the transmission lines by electromagnetic waves. The high-frequency signals used for communication are distinct from the low-frequency electromagnetic waves produced by high-voltage AC power transmission lines, which typically have frequencies of 50 or 60 Hz and can cause energy loss in long-distance power transmission. Instead, for communication purposes, signals are transmitted using variations in the wave's amplitude (AM), frequency (FM), or phase to carry information.
These high-frequency signals travel along transmission lines where the incoming charge effectively pushes other charges ahead of it, creating a rapidly propagating change in the electric field. This phenomenon allows signals to be transmitted at nearly the speed of light through the transmission lines, making the system highly efficient for conveying information over long distances.
It's important to maintain high voltages in long-distance transmission to reduce power losses. To achieve efficient power distribution, AC voltage is typically used, as it is easier to adjust to the required levels for various applications.