How does a transformer lessen voltage? — C
When you send an alternating current through the primary coil of wire in a transformer, that current produces a magnetic field in the transformer. Because the current in the primary coil is changing with time—it’s an alternating current—this magnetic field is changing and changing magnetic fields are accompanied by electric fields. In the transformer, this electric field pushes electric charges around the secondary coil of wire in the transformer. Since these electric charges are pushed in the direction they are traveling, work is being done on them and their energies are increasing. However, in the transformer you mention, the secondary coil of wire has fewer turns in it that the primary coil of wire. As a result, the charges don’t receive as much energy per charge (as much voltage) as the charges in the primary coil are giving up. This type of transformer, in which the secondary coil has fewer turns of wire than the primary coil, is called a step-down transformer and reduces the voltage of an alternating current.