A transformer is a device that uses the principle of electromagnetic induction to change alternating voltage. It is mainly composed of a primary coil, a secondary coil and a core (magnetic core). Its core function is to achieve voltage transformation, to meet the specific voltage requirements of different electrical equipment, and also to play roles such as electrical isolation, voltage stabilization, and impedance matching.
From a technical perspective, when an alternating current is passed through the primary coil, a varying magnetic flux will be generated in the iron core. This varying magnetic flux will simultaneously pass through both the primary and secondary coils. According to the law of electromagnetic induction, an induced electromotive force will be generated in each of the two coils. If the number of turns in the secondary coil is different from that in the primary coil, the output voltage of the secondary coil will be different from the input voltage of the primary coil. The ratio of turns determines the ratio of voltage transformation. For example, if the number of turns in the primary coil is 100 and the number of turns in the secondary coil is 200, when the input voltage of the primary coil is 220V, the theoretical output voltage of the secondary coil will be 440V.