A type of smoke detector which used a small amount of radioactive material is the

A type of smoke detector which used a small amount of radioactive material is the

• A. Ionization Detector
• B. Photoelectric Detector
• C. Calorimetric Detector
• D. Acoustic Detector

Answer: (A)

Ionization detectors rely on ionization of the air inside a sensing chamber by a small sealed amount of radioactive material. This material, typically americium-241, creates a steady current between two electrodes. When smoke enters the chamber, the smoke particles attach to the ions and reduce the current, causing the detector to trip the alarm. This design tends to detect flaming, fast-burning fires quickly because the fine combustion particles more readily disrupt the ion flow. In contrast, photoelectric detectors use a light beam and a sensor to detect smoke by scattering light, with no radioactive source. Calorimetric (heat) detectors respond to temperature rise, and acoustic detectors listen for abnormal sounds—none of these rely on radioactive material.

Ionization detectors rely on ionization of the air inside a sensing chamber by a small sealed amount of radioactive material. This material, typically americium-241, creates a steady current between two electrodes. When smoke enters the chamber, the smoke particles attach to the ions and reduce the current, causing the detector to trip the alarm. This design tends to detect flaming, fast-burning fires quickly because the fine combustion particles more readily disrupt the ion flow.

In contrast, photoelectric detectors use a light beam and a sensor to detect smoke by scattering light, with no radioactive source. Calorimetric (heat) detectors respond to temperature rise, and acoustic detectors listen for abnormal sounds—none of these rely on radioactive material.