Technician Handbook 623 Electrical Circuit Diagnosis Component Resistances All materials have some resistance, even conductors. The resistance of conductors, however, is very low. Wiring, fuses and switches in a circuit normally have less than 1/10 of an ohm (0.1 Ω) resistance. Loads Loads are the devices in a circuit that use electricity to perform work . The purpose of the circuit is to deliver the electrical current necessary to operate the load. Typical loads include: • Lamps • Motors • Horn • Defogger • Audio speakers • Cigarette lighter Other devices that can act as a load in a circuit are resistors .
Resistors are electronic devices that add resistance to a circuit to control current flow . A blower motor control switch is an example. It has several resistance levels to control current flow to the blower motor and thus control blower speed. The loads in a circuit – whether working loads or resistors – will have the most resistance of all the components in the circuit. Technical Training 13