An inductive electrical device for changing the voltage of alternating current.
A transformer consists of two magnetically coupled coils. Alternating current in one (called the "primary") creates a changing magnetic field which induces a current in the second coil (the "secondary"). A core made of iron or ferrite generally connects the two coils, but higher frequency devices can work without a ferrous core.
Transformers have two primary functions: Voltage transformation and isolation: Isolation refers to the fact that the coils are connected only by a magnetic field, so they can be independent of a common ground.
