A. voltage device

A power transformer is a voltage device because its primary function is to change the voltage level of an electrical circuit. It does this by using electromagnetic induction to transfer energy from one circuit to another. The transformer has two coils, the primary and the secondary, which are separated by an iron core. When an alternating current is applied to the primary coil, it induces a magnetic field which in turn induces a current in the secondary coil. The voltage in the secondary coil is determined by the ratio of the number of turns in the primary and secondary coils. The transformer can raise or lower the voltage level depending on the desired application.