Automotive Service Technician Period 1 Practice Exam

Resistive loads draw current in proportion to the applied voltage and convert energy primarily into heat or light without storing much energy in the circuit. In automotive circuits, lighting is the classic example because a filament resistor simply heats up as current passes, following Ohm’s law. Radios, when powered, also behave as resistive loads in the sense that the power supply presents a fairly steady impedance, so the current drawn at a given voltage is fairly predictable. This contrasts with inductive loads like motors or coils, where energy is stored in a magnetic field and the current can lag the voltage. Since resistive loads do require current to operate, the statement that they require no current is incorrect, and they aren’t necessarily active only when the ignition is on—lighting and radios can be powered in other key positions or states as well.