Transformers are a type of passive component that can be used to transfer electrical energy from one circuit to another, or to multiple circuits. They can also change the voltage of alternating current. A transformer consists of two magnetically coupled coils, known as the primary and secondary. A core of iron or ferrite connects the two coils, but high frequency devices can function without a ferrous core.
Transformers modify the voltage between circuits through a process called electromagnetic induction, which is typically used to increase (step up) or decrease (step down) the voltage levels between circuits.
Transformers can be used in various applications, such as reducing the voltage of a power circuit to operate low-voltage devices. They are essential for transmission, distribution and utilization of alternating current electric power.