Question

A soldering iron is plugged into a household outlet. A circuit breaker protects the circuit that the wall outlet is on by opening the circuit when more than 15 amps of current is drawn in the circuit. The soldering iron has about 150 amps of current flowing in its tip when it is on. Clearly explain how this is possible.

Answer 1

The Soldering Iron consists a component step down transformer which steps down the voltage on the secondary side to 8 V ,whose primary is plugged into household outlet of 120 V AC which converts the current drawn from the primary for example say 10 A to 150 A on secondary side of current flowing in its tip when it is on.So that power on both primary and secondary remain equal

From Transformer turns ratio

Vs/Vp = Ip/Is

Vs =120*(10/150) =8 V

P_primary =VpIp =120*10 =1200 W

P_secondary =VsIs =8*150 =1200 W