Transformer

A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Transformers are used to increase or decrease the alternating voltages and currents in electric power applications. A varying current in the transformer's primary winding creates a varying magnetic flux in the core and a varying magnetic field on the secondary winding. This induces voltage in the secondary winding. The primary and secondary windings are wrapped around a core of infinitely high magnetic permeability. The transformer winding voltage ratio is directly proportional to the winding turns ratio.

In our model the secondary coils has much less turns than primary coil. The ends are joined together by the points of two nails touching each other. This is a step down transformer for the voltage. That means the secondary current will be higher. If the ratio of the number of coils on the primary to the number of coils on the secondary is so high enough the current is huge. It could melt the ends of the nails and weld them together.