impedance Z1 is, in fact, the effective load impedance seen by the source. Impedance matching is sometimes the primary
function of the transformer. However, regardless of the function, the impedance seen from the primary or the effective
impedance in the primary circuit depends on the turn ratio squared and the impedance of the secondary.
Although an actual transformer includes losses due to resistance of the conductors, induced currents in the core, and
currents needed to magnetize the core (as well as capacitive losses), the main approximation used to define an ideal
transformer was the assumption that the permeability is infinite and, therefore, that the reluctance of the magnetic path is
zero. In practical applications, this is never the case, and in some transformers, like air-core transformers, the above
approximations cannot be used at all. In many transformers, the losses are relatively small (sometimes less than 1%) and the
above approximations are quite good. However, in low-power transformers, losses may be high relative to the total power
capacity of the transformer.