Resistors are used to limit voltage and/or current in a circuit and can have a fixed or variable resistance.  Variable resistors (often called potentiometers or rheostats) are used when dynamic control over the voltage/current in a circuit is needed, for example, in a light dimmer or volume control.

An inductor is coiled wire that stores electric energy in the form of magnetic energy and resists changes in the electric current flowing through it. If current is increasing, the inductor produces a voltage that slows the increase and, if current is decreasing, the magnetic energy in the coil opposes the decrease to keep the current flowing longer. In contrast to capacitors, inductors allow DC to pass easily but resist the flow of AC.

Connecting the 6 batteries in series multiplies their voltage while keeping their current the same yielding a 36V 20A configuration. Connecting the 6 batteries in parallel multiplies their current while keeping their voltage the same yieleding a 6V 120A configuration. Using a series-parallel connection, 3 batteries can be connected in series and 3 can be connected in parallel resulting in a 18V 60A configuration.

The joule is a unit of measurement for energy.

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.