Which statement about smoke detector technology is true?

Which statement about smoke detector technology is true?

• A. Ionization detectors respond faster to flaming fires
• B. Photoelectric detectors respond faster to flaming fires
• C. Both detector types are equally responsive to all fire types
• D. Photoelectric detectors require no power

Answer: (A)

Smok e detector technology differs in how quickly it reacts to different kinds of fires. Ionization detectors use a small radioactive source to create a steady current between two plates; when smoke enters the chamber, the current is disrupted and the alarm goes off. Flaming fires produce many tiny particles and rapidly changing flames, which quickly interfere with that current, so ionization detectors tend to alarm faster for flaming fires. Photoelectric detectors shine a light and look for smoke that scatters the light into the sensor; they are more responsive to the larger volumes of visible smoke typical of smoldering fires, not fast flames. Therefore, the statement that ionization detectors respond faster to flaming fires is the best fit. The other claims don’t match how these technologies work—photoelectric detectors aren’t inherently faster for flaming fires, the two types aren’t equally responsive to all fire types, and detectors do require power to operate.

Smok e detector technology differs in how quickly it reacts to different kinds of fires. Ionization detectors use a small radioactive source to create a steady current between two plates; when smoke enters the chamber, the current is disrupted and the alarm goes off. Flaming fires produce many tiny particles and rapidly changing flames, which quickly interfere with that current, so ionization detectors tend to alarm faster for flaming fires. Photoelectric detectors shine a light and look for smoke that scatters the light into the sensor; they are more responsive to the larger volumes of visible smoke typical of smoldering fires, not fast flames. Therefore, the statement that ionization detectors respond faster to flaming fires is the best fit. The other claims don’t match how these technologies work—photoelectric detectors aren’t inherently faster for flaming fires, the two types aren’t equally responsive to all fire types, and detectors do require power to operate.