# Why are transformer windings made from conductors of different diameters?

Due to the fact that the power losses in the transformer are usually small, it can be roughly assumed that the powers in the primary and secondary windings are the same. In this case, it can be assumed that the currents in the transformer windings are approximately inversely proportional to the voltages: I1 / I2 = U2 / U1 or that the currents in the transformer windings are inversely proportional to the number of turns of the primary and secondary windings: I1 / I2 = N1 / N2. This means that in the step-up transformer the current in the secondary winding is less than in the primary (as many times as the voltage U2 is greater than the voltage U1), and in the step-down transformer the current in the secondary winding is greater than in the primary. Therefore, in transformers, high voltage windings are made of thinner wires than low voltage windings.