Electricity is delivered from power stations to customers as AC because it provides a more efficient way to transport electricity over long distances. A line drop is a decrease in voltage between two points on an electrical transmission line due to resistance in the line. A lower current and higher voltage across the line will help compensate for the line drop.

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.

A schematic is the proper name for a drawing of an electric or electronic circuit.

Connecting the 4 batteries in series multiplies their voltage while keeping their current the same yielding a 36V 5A configuration. Connecting the 4 batteries in parallel multiplies their current while keeping their voltage the same yieleding a 9V 20A configuration. Using a series-parallel connection, 2 batteries can be connected in series and 2 can be connected in parallel resulting in a 18V 10A configuration.

Electrons flow from an area of high concentration to an area of low concentration. A high voltage indicates a high concentration of electrons that creates a greater potential for electron flow than a low voltage. When applied to a load, voltage creates electricity and potential difference is the measure of voltage at a specific location in an electrical circuit.