How does power plant make electricity?
The basic idea at work in a transformer is that each turn of winding around the magnetic core has the same AC voltage across it. This is because the voltage produced by a turn of winding is proportional to the rate of change of the magnetic flux passing through the magnetic core material of the transformer, and all the turns have just about the same magnetic flux passing through the cure in the middle of those turns. So a higher voltage winding must have more turns of wire than a lower voltage winding. Put a low voltage across a few turns and you get a higher voltage out across a higher number of turns (step up transformer). Put a high voltage across a large number of turns and you get a lower voltage out across a smaller number of turns (step down transformer). The generators that make the voltage at the power plant also use the rate of change of magnetic flux to make voltage but produce the rate of change by having a steady magnetic field that they spin inside the wires, so that the
