A transistor works by allowing a small amount of current applied at the base to control general current flow from collector to emitter through the transistor.

Conductors are elements that allow electrons to flow freely. Their valence shell is less than half full of electrons that are able to move easily from one atom to another.

All conductors have resistance and the amount of resistance varies with the element. In general, metals make the best conductors of electricity and non-metals make the worst conductors of electricity.

Capacitors store electricity and are used in circuits as temporary batteries. Capacitors are charged by DC current (AC current passes through a capacitor) and that stored charge can later be dissipated into the circuit as needed. Capacitors connected in series produce less capacitance than capacitors connected in parallel.

Connecting the 4 batteries in series multiplies their voltage while keeping their current the same yielding a 48V 20A configuration. Connecting the 4 batteries in parallel multiplies their current while keeping their voltage the same yieleding a 12V 80A configuration. Using a series-parallel connection, 2 batteries can be connected in series and 2 can be connected in parallel resulting in a 24V 40A configuration.