what is a transformer

A transformer is an electrical device that transfers electrical energy from one circuit to another circuit or multiple circuits. It is used to either increase or decrease the voltage of an alternating current (AC) power supply. The basic transformer comprises three parts: the magnetic core, the primary winding, and the secondary winding. The primary winding is connected to a live source of AC power, which produces an alternating magnetic field that surrounds the winding. This induces an electromotive force (EMF) in the secondary winding. If the circuit of the secondary winding is closed, then AC current will flow through it. Transformers are used to change AC voltage levels, such transformers being termed step-up or step-down type to increase or decrease voltage level, respectively. They can also be used to provide galvanic isolation between circuits as well as to couple stages of signal-processing circuits. Transformers are essential for the transmission, distribution, and utilization of alternating current electric power. The principle behind transformers is electromagnetic induction, which states that a changing magnetic field will induce a voltage in a conductor.