A transformer is an electrical device that takes electricity of one voltage and changes it into another voltage. A power transformer consists of a coil wrapped around an electromagnet that transfers electricity from one circuit to another without changing the frequency of the electric energy.
A transformer changes electricity voltage using the properties of electricity. In an electric circuit, there is magnetism around it. Whenever a magnetic field changes, a voltage is made. Although the frequency of the electrical energy isn’t changed, the voltage and current commonly change when passing through.