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How do transformers use magnetic fields to change voltage?

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Learn about magnetic fields and the levels of particles, atoms, crystals, and domains — magnet Magnetic fields and the levels of magnetism of particles, atoms, crystals, and domains.

Transformers change voltage through electromagnetic induction. When an alternating current flows through the primary coil, it creates a changing magnetic field that induces a current in a secondary coil.12

In a typical transformer, these coils are wound around an iron core, which confines the magnetic flux and ensures that nearly all magnetic lines of force pass through both circuits. Because each turn of the coils experiences the same magnetic flux, the voltage induced in the secondary coil is proportional to the number of turns in that coil relative to the primary coil. This relationship is defined by the turns ratio:21

$\frac{V_{2}}{V_{1}} = \frac{N_{2}}{N_{1}}$

By adjusting the ratio of turns ( $N_{2} / N_{1}$ ), a transformer can either step up or step down the voltage to meet specific power transmission or operational needs. To maintain efficiency, the iron core is often laminated to minimize eddy currents, which are undesirable circulatory currents that generate heat.123