Basic principles

The transformer is based on two principles: first, thatFMLG12

 an electric current can produce a magnetic field (electromagnetism), and, second that a changing magneticmat-02eh

 field within a coil of wire induces a voltage across the ends of the coil (electromagnetic induction). Changing the current in theSM5964C40PP

 primary coil changes the magnetic flux that is developed. The changing magnetic flux induces a voltage in the secondary coil.An idealBU407

 transformerAn ideal transformer is shown in the adjacent figure. Current passing through the primary coil creates a magnetic field. The primary and secondary coils are2sj380

 wrapped around a core of very high magnetic permeability, such as iron, so that most of the magnetic flux passes through both the primary and secondary coils.