Electronic heat detectors utilize ______, which are electronic components that change resistance based on ambient temperature.

Electronic heat detectors utilize ______, which are electronic components that change resistance based on ambient temperature.

• A. Photodiodes
• B. Capacitors
• C. Resistors
• D. Thermistors

Answer: (D)

The idea being tested is using a component whose resistance changes with temperature to sense ambient heat. A thermistor is exactly that: a resistor whose value varies strongly with temperature, making it ideal for detecting temperature changes in a heat detector. In typical designs, an NTC thermistor is used, where resistance decreases as temperature rises; the detector’s circuitry monitors this change and triggers when a set threshold is reached. Photodiodes are sensitive to light, not temperature. Capacitors store charge and aren’t used to sense ambient temperature in this context. A regular resistor has a fixed resistance and isn’t relied upon to reliably respond to temperature changes unless it’s specifically a thermistor.

The idea being tested is using a component whose resistance changes with temperature to sense ambient heat. A thermistor is exactly that: a resistor whose value varies strongly with temperature, making it ideal for detecting temperature changes in a heat detector. In typical designs, an NTC thermistor is used, where resistance decreases as temperature rises; the detector’s circuitry monitors this change and triggers when a set threshold is reached.

Photodiodes are sensitive to light, not temperature. Capacitors store charge and aren’t used to sense ambient temperature in this context. A regular resistor has a fixed resistance and isn’t relied upon to reliably respond to temperature changes unless it’s specifically a thermistor.