ABSTRACT
Transformers are generally used to change voltages levels – such as those at mains level to those required by electronic circuits.
Let us assume:
• the secondary terminals are initially open • all the flux is confined to the iron core so that flux is same in each coil • resistance of windings can be neglected
Considering the primary coil:
Any voltage that appears across the terminals of the coil (effectively an inductor) must be due to the self-induced voltage (back emf) in the coil by a changing current through it (self-inductance).
