A simple iron-cored transformer is illustrated in the figure below.
State why the primary and secondary coils are wound on a core made of iron.
Suggest why thermal energy is generated in the core when the transformer is in use.
The root-mean-square (r.m.s.) voltage and current in the primary coil are 
and 
respectively. The r.m.s. voltage and current in the secondary coil are 
and 
respectively.
Explain, by reference to direct current, what is meant by the root-mean-square value of an alternating current.
Show that, for an ideal transformer,
