What device is used to increase or decrease voltage in an electrical circuit?

The device used to increase or decrease voltage in an electrical circuit is the transformer. A transformer operates on the principle of electromagnetic induction and consists of coils of wire, known as windings, wrapped around a core. By varying the number of turns in the primary and secondary windings, a transformer can step up (increase) or step down (decrease) the voltage.

When alternating current flows through the primary winding, it creates a magnetic field that induces a voltage in the secondary winding. If the secondary winding has more turns than the primary, the output voltage is higher than the input voltage, and conversely, if it has fewer turns, the output voltage is lower. This ability to change voltage levels efficiently is essential for various applications, including power distribution and electronic devices.

In contrast, an inverter is used to convert direct current (DC) to alternating current (AC) rather than to directly modify voltage levels. A resistor does not change voltage; it simply limits current flow and dissipates energy as heat. A capacitor is primarily used for storing electrical energy and smoothing voltage fluctuations but is not specifically designed to change voltage levels in the way that a transformer is.