A (n) detector is one which responds to rapid changes in temperature.

• A. Photoelectric
• B. Ionization
• C. Rate-of-rise
• D. Fixed-temperature

Answer: (C)

Detectors that respond to rapid changes in temperature are rate-of-rise heat detectors. They trigger not when a single temperature threshold is reached, but when the temperature climbs quickly—often around a preset rate like 15°F per minute above ambient. This makes them effective for fast-developing, flaming fires where heat spikes rapidly, even if the overall temperature hasn't reached a very high value yet. By contrast, fixed-temperature detectors go off at a specific temperature, so slow or smoldering fires may not trigger them until that exact heat level is reached. Photoelectric and ionization detectors, on the other hand, detect smoke and combustion particles rather than rapid temperature changes.