Question

A hair dryer uses 10A at 120V. It is used with a transformer in England, where the voltage is 240V. A. What should be the ratio of the turns of the transformer? B. What current will the hair dryer now draw?

Answer 1

A. Np/Ns = 240 /120 = 2/1 = Turns ratio.

Np = Turns on primary winding.
Ns = Turns on secondary winding.

B. Pr = VI = 120 * 10 = 1200W = rated
power.

240I = 1200W,
I = 1200/ =240 = 5Amps.

Answer 2

Thanks Henry