A transformer is a system that uses the principle of electromagnetic induction to increase or decrease voltage in adjacent electrical circuits. Transformers are incredibly useful because they quickly change voltage depending on the setting that requires it. For example, high voltages transmit electrical currents across long distances, such as between telephone poles. But they must be decreased before they enter a home, because extremely high voltages aren’t safe for standard household electrical circuits.
A transformer has at least two electrical circuits that sit next to each other. The adjacent sides of the circuit have a coiled segment with a number of coils, formally known as turns, which must correspond to the voltage produced through a certain ratio. If a primary circuit has coils with 60 turns, and the secondary circuit has only 15, the ratio of the two circuits is four to one, and every voltage that is transformed will be brought down by four times.
With the system of electromagnetic induction, changing voltages through electromagnetic force, current actually lowers where voltage increases. This means that, though the force of voltage is much higher in such transmissions, the current is lessened, and resistance and heat will also be lower. That’s ideal for transmitting electrical signals through cable, because the wires will be less likely to overheat or be overpowered by current.
Transformers only use alternating electrical current, not direct. Alternating current (AC) changes directions frequently, using electromagnetic forces to switch between poles in a circuit. The change in charge forces the circuit to begin moving the opposite direction. In contrast, direct current (DC) never changes direction; it travels in the same direction consistently. Alternating current, with its waveform fluctuation, is often better for cross-country electrical signals because its electromagnetic changes allow it to be transformed to a different voltage easily. DC requires extra steps to change voltage.