 So Faraday set up almost exactly this experiment, except instead of a permanent magnet here, he used an electro magnet. So instead of having one coil and a magnet, he had two coils, and one was attached to a battery, and one was attached to an ammeter. And he found that he didn't get any current in the second coil when he just left the first coil sitting there, unsurprisingly. More surprisingly to him, when he connected the battery to the first coil and left it running, he also didn't see anything in the second coil, except for a little flicker when he first connected it. And then when he disconnected it, he got a little flicker again in the opposite direction. And so he was getting an electric field running around that loop, only when he was changing the magnetic field that was going through that loop. And so Faraday's discovery of this process, which was called induction, so called because the changing current in one loop induced a current in the other loop, and it was James Maxwell and Oliver Heaviside, who later went on to quantify that and really describe exactly what was going on. And it turns out that exactly what was going on was that it wasn't just the magnetic field, because the magnetic field is different at different points. So at different points throughout this entire loop, there's different magnetic fields. And even at different points of this coil, there might be different magnetic fields. And it turns out that what's important is not the field at a particular point, but the whole magnetic flux going through that loop. And we'll discuss exactly what that is in a minute. And the changing magnetic flux causes a force to act on the charges going around here. And this is an electric force. So we've got an electric field going around. And we know that if we have an electric field, that's a force-punit charge. And if the charges go around at a certain distance, then they get a certain amount of energy-punit charge. And energy-punit charge is an electric potential. So we get another potential difference going around this loop based on the amount of changing magnetic flux we have.