Resistance is opposition to the flow of current and is measured in ohms (Ω). One ohm is defined as the amount of resistance that will allow one ampere of current to flow if one volt of voltage is applied. As resistance increases, current decreases as resistance and current are inversely proportional.

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. A transistor acts as a gate or switch for electronic signals.

In contrast to the constant one-way flow of direct current, alternating current changes direction many times each second. Electricity is delivered from power stations to customers as AC because it provides a more efficient way to transport electricity over long distances.

Connecting the 6 batteries in series multiplies their voltage while keeping their current the same yielding a 90V 20A configuration. Connecting the 6 batteries in parallel multiplies their current while keeping their voltage the same yieleding a 15V 120A configuration. Using a series-parallel connection, 3 batteries can be connected in series and 3 can be connected in parallel resulting in a 45V 60A configuration.