Since most lighting systems utilize a transformer that converts AC voltage to DC voltage,I'll stick with the DC side of things. Voltage= The amount of energy required to move an amount of electrical charge.The symbol for Voltage is (E) Electric circuit = A minimum of three components are required for all electric circuits:a source of energy,a load,and connecting wires. Electron current = The quantity of electric charges that move past a given point during a period of 1 second(s).The symbol for current is (I) Resistance = A factor in elelctrical circuits that is similar to mehcanical friction.The purpose of resistance is to limit or control the amount of electic current in a system.(Lights are a source of resistance.The wire in the bulb is high in resistance,so it generates friction or heat.In turn the wire glows from this and generates light.)The symbol for resistance is (R) Ohm= A practical unit of measurement of electrical resistance. Conductance= The description of the ability or ease with which a material conducts current.