The way transformers change voltage relies on the most fundamental law of electromagnetism discovered: a change in an electric current in a wire creates a magnetic field. The reverse can happen ...

This magnetic field changes as the current changes ... The induced voltage causes an alternating current to flow. Transformers can only work with alternating current. Input and output voltages ...

How a tokamak works: The electric field induced by a transformer drives a current (big red arrows) through the plasma column. This generates a poloidal magnetic field that bends the plasma current ...