The transformer is made according to the principle of electromagnetic induction. There are two windings, a primary windings and a secondary windings on top of the closed iron core. When the original winding plus AC power supply voltage.

There is alternating current in the current of the original Rao group, but when the magnetic potential is established, the alternating main magnetic flux will be generated in the iron core under the effect of the magnetic potential, and the main magnetic flux will pass through the iron core simultaneously, the primary and secondary windings close because of electromagnetic induction in the primary and secondary windings produce electromotive force, as to why it can boost and depressurize? It is necessary to use LENZ’s law to explain that the magnetic flux produced by the induced current always blocks the change of the original magnetic flux. When the original magnetic flux increases, the magnetic flux produced by the induced current is opposite to the original magnetic flux, that is to say, the induced magnetic flux produced by the secondary winding is opposite to the main magnetic flux produced by the original winding, so the secondary winding has a low grade alternating voltage so the iron core is the magnetic circuit part of the transformer and the winding is the circuit part of the transformer.