Handbook 652 Body Electrical Diagnosis Resistance and Current The resistances in a series circuit add up to the total circuit resistance. Assuming a fixed 12.6V power supply, the current in the circuit is determined by total circuit resistance . Since there is only one path, current is the same at every point in the circuit. Adding excessive resistance in the circuit reduces current flow in the circuit. The resistance can be on either the power or ground side of the load and still cause the same reduction in current that leads to circuit problems. Series Circuit General Rules A true series circuit has only one current path regardless of the number of loads in the circuit.
• If there is only one load in the circuit, all the voltage drop is in that load. • If there are two or more loads in a circuit, voltage drop is divided proportionally between them according to the resistance of the loads. • The load with the highest resistance has the highest voltage drop. The load with the lowest resistance has the lowest voltage drop. • Current is the same everywhere in the circuit. An ammeter can be connected anywhere in the circuit to measure current. 38 Technical Training