Transformers are devices used to increase or decrease AC voltages with very little waste of
energy. Step-up transformers allow a device such as a television tube, which may need
25,000 V, to get the voltage it needs from a wall outlet that usually supplies only 120 V.
Likewise, a step-down transformer can allow a small device, such as a battery charger, to be
supplied from the same outlet with as little as 1.5 V.
Imagine that you had to construct a transformer capable of running a television set that was
going to be plugged into a conventional 120 V outlet that was on a 15 A line. On the primary
coil of your transformer are 200 turns.
1. How many turns will you need on your secondary coil if the television needs 25,000 V to
function?