N.32 More on Maxwell’s third law

Since the voltage is minus the integral of the electric field, it might seem that there is a plus and minus mixed up in figure 13.5.

But actually, it is a bit more complex. The initial effect of the induced electric field is to drive the electrons towards the pole marked as negative. (Recall that the charge of electrons is negative, so the force on the electrons is in the direction opposite to the electric field.) The accumulation of electrons at the negative pole sets up a counter-acting electric field that stops further motion of the electrons. Since the leads to the load will be stranded together rather than laid out in a circle, they are not affected by the induced electric field, but only by the counter-acting one. If you want, just forget about voltages and consider that the induced electric field will force the electrons out of the negative terminal and through the load.