As transmission temperature increases, what happens to a thermistor's resistance?

As transmission temperature increases, what happens to a thermistor's resistance?

• A. Resistance increases
• B. Resistance stays constant
• C. Resistance decreases
• D. Resistance becomes infinite

Answer: (C)

Thermistors change resistance with temperature, and the common automotive sensor type is an NTC (negative temperature coefficient), where resistance falls as temperature rises. As transmission temperature increases, the semiconducting material has more charge carriers available and becomes more conductive, so the resistance decreases. If resistance increased with temperature, that would describe a PTC thermistor, not the typical sensor used here. If it stayed constant, there would be no temperature dependence, which isn’t the case for a thermistor. If it became infinite, that would indicate an open circuit or device failure, not normal thermistor behavior.

Thermistors change resistance with temperature, and the common automotive sensor type is an NTC (negative temperature coefficient), where resistance falls as temperature rises. As transmission temperature increases, the semiconducting material has more charge carriers available and becomes more conductive, so the resistance decreases.

If resistance increased with temperature, that would describe a PTC thermistor, not the typical sensor used here. If it stayed constant, there would be no temperature dependence, which isn’t the case for a thermistor. If it became infinite, that would indicate an open circuit or device failure, not normal thermistor behavior.