The efficiency e of a transformer is defined as the ratio of the power output to the power input, or e = Ps/PP.
(a) Show that for an ideal transformer, this expression gives an efficiency of 100%(e = 1.00).
(b) Suppose a step-up transformer increased the line voltage from 120 to 240 V, while at the same time the output current was reduced to 5.0 A from 12 A. What is the transformer’s efficiency? Is it ideal?