Which of the following is not typically considered a simple resistive load in automotive electrical circuits?

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Multiple Choice

Which of the following is not typically considered a simple resistive load in automotive electrical circuits?

The main idea is that a simple resistive load follows Ohm’s law: current is proportional to voltage with little change due to speed or other factors. A light bulb fits this idea since it mainly behaves like a resistor, even though its resistance increases as it heats. A starter motor, on the other hand, is a DC motor. It has inductive windings and produces back-EMF as it spins. That back-EMF opposes the applied voltage and reduces current as the motor speeds up. The current drawn is therefore not governed by a fixed R value and changes with speed, so it’s not a simple resistive load. A radio contains electronics and regulators, which makes its input behavior more complex than a pure resistor, and a headlight switch is a control device rather than a load itself (the lamps are the load). But the option that best fits “not a simple resistive load” is the starter motor.

The main idea is that a simple resistive load follows Ohm’s law: current is proportional to voltage with little change due to speed or other factors. A light bulb fits this idea since it mainly behaves like a resistor, even though its resistance increases as it heats.

A starter motor, on the other hand, is a DC motor. It has inductive windings and produces back-EMF as it spins. That back-EMF opposes the applied voltage and reduces current as the motor speeds up. The current drawn is therefore not governed by a fixed R value and changes with speed, so it’s not a simple resistive load.

A radio contains electronics and regulators, which makes its input behavior more complex than a pure resistor, and a headlight switch is a control device rather than a load itself (the lamps are the load). But the option that best fits “not a simple resistive load” is the starter motor.

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