Transformers function to change voltage or current from low to high or from high to low. The symbol nicely illustrates the internal workings of a transistor, which consists of a pair of coils wrapped around a core.

The secondary voltage – or the output voltage – of a transformer can be expressed mathematically as follows. In this equation, V stands for voltage, E stands for the induced voltage and N stands for the winding turns ratio.

Vp/Vs = Ep/Es = Np/Ns = a.