Transformer design is based on some simple physical principles like
Faraday's and Ampere's laws, which are integral formulations of some
Maxwell's equations. Intuitively, a transformer is a device in which
two windigns are mutually coupled by a common magnetic flux, the
currents adjusting themselves in order to mimize it. We will show in
the following that for a perfect transformer with turns on the input
and
turns on the output, the ration between input and ouput
voltages is
, while the currents ration is
. From
those relations, it can be deduced that an input impedance Z appears
as
on the ouput. This ability to transform impedances
will be crucial in audio applications.