A transformer with a single 12-volt secondary draws 0.5 amperes through its 120-volt primary. Assuming no losses, what current is drawn from the secondary?

In an ideal transformer with no losses, the power entering the primary winding is exactly equal to the power leaving the secondary winding (Power_primary = Power_secondary). First, calculate the total power in the primary circuit using P = E × I. Multiplying 120 volts by 0.5 amperes gives a total power of 60 watts. Because the secondary power must also be 60 watts, you can find the secondary current by rearranging the power formula to I = P / E. Dividing 60 watts by the 12-volt secondary voltage gives exactly 5 amperes. Alternatively, you can recognize that since the voltage is stepped down by a factor of 10 (120V to 12V), the current must be stepped up by that same factor of 10 (0.5A to 5A).