Working principle of transformer

According to Faraday's law of electromagnetic induction and Lenz's law, the simple explanation is as follows: when the current in the original coil (that is, the group of coils that are already electrified) increases, the magnetic field generated by the coil in the iron core also increases (the direction of the magnetic field can be judged by the right-hand screw rule). At this time, the induced current will be generated on the auxiliary coil (that is, the group of coils that are not electrified originally), and the induction current will increase The direction of the current is opposite to that in the original coil (the result is that the direction of the magnetic field generated by the current in the secondary coil is opposite to that in the original coil).

When the current in the original coil is decreasing, the magnetic field generated by the current in the iron core is also weakening. At this time, the current in the secondary coil is in the same direction as the current in the original coil, and the magnetic field generated by the current in the iron core is in the same direction as the magnetic field generated by the original coil in the iron core.

In this way, due to the change of current in the original coil, the current is generated in the secondary coil. This is how the transformer works.