What happens when you put an inductor and a capacitor in a circuit? Something kind of cool—and actually important. You can make all sorts of different types of inductors, but the most common type is cylindrical coil of wire—a solenoid. When current runs through the first loop, it creates a magnetic field that passes through the other loops. Magnetic fields don’t really do anything unless the the magnitude changes. A changing magnetic field will create an electric field in the other loops. The direction of this electric field will make a change in electric potential that acts like a battery. In the end, we have a device that has a potential difference that is proportional to the time rate of change of the current (since the current makes the magnetic field). This can be written as: There are two things to point out in this equation. First, the L is the inductance. It only depends on the geometry of the solenoid (or whatever shape you have) and its value is measured in Henry’s. Second, there is the negative sign. This means the change in potential across the inductor opposes the change in current. How does an inductor behave in a circuit? If you have a constant current...