A moving electric current produces a magnetic field proportional to the amount of current flow. This magnetic field can be made stronger by winding the wire into a coil and further enhanced if done around an iron containing (ferrous) core.

Direct current flows in only one direction in a circuit, from the negative terminal of the voltage source to the positive. A common source of direct current (DC) is a battery.

Circuits containing transistors are packaged into integrated circuit chips that allow encapsulating complex circuit designs (CPU, memory, I/O) for easier integration into electronic devices and machines.

All electricity is the movement of electrons which are subatomic particles that orbit the nucleus of an atom. Electrons occupy various energy levels called shells and how well an element enables the flow of electrons depends on how many electrons occupy its outer (valence) electron shell.

Inductance is a property of an AC circuit (or a component in an AC circuit) that quantifies resistance to changes in current. The current in an AC circuit is continuously changing and inductive reactance (the opposition to change) depends both on the inductance of the circuit or component and the rate at which the current is changing.