Question

You have taken physics and you know that household circuits usually have circuit
breakers limiting current to 20 A or less. You also know that pacemakers can be
influenced by external electric or magnetic fields. If a pacemaker is safe for magnetic
fields of 1 mT and below, how close can someone wearing a pacemaker get to a wire
inside of a home?

Answer 1

The induction of the infinite conductor is divided as B = mm0*I/2*3.14*R. Thus, R = mm0*I/2*3.14*B = 4*10^-3 m or 4 mm. You actually cannot use pacemaker closer than 4 mm out of the wire with 20 A.