Ionization Smoke Detectors work by:

Ionization Smoke Detectors work by:

• A. A device containing a small amount of radioactive material that ionizes the air between two charged electrodes to sense the presence of smoke particles
• B. A device containing a photoelectric sensor to detect smoke.
• C. Detects smoke by flame detection.
• D. Detects smoke by ultrasonic vibrations.

Answer: (A)

Ionization smoke detectors operate by placing a small amount of radioactive material between two electrodes to ionize the air, creating a constant current. When smoke enters the chamber, the smoke particles attach to the ions, reducing the ion flow and the current, which triggers the alarm. The radioactive source—commonly americium-241—is what makes the ionization possible. The other options describe different sensing methods: a photoelectric detector uses a light beam and a sensor to detect smoke, flame detection looks for flame signatures, and ultrasonic methods aren’t used for smoke sensing. Ionization detectors respond quickly to small, fast-burning particles, which is why this mechanism is the correct description.

Ionization smoke detectors operate by placing a small amount of radioactive material between two electrodes to ionize the air, creating a constant current. When smoke enters the chamber, the smoke particles attach to the ions, reducing the ion flow and the current, which triggers the alarm. The radioactive source—commonly americium-241—is what makes the ionization possible. The other options describe different sensing methods: a photoelectric detector uses a light beam and a sensor to detect smoke, flame detection looks for flame signatures, and ultrasonic methods aren’t used for smoke sensing. Ionization detectors respond quickly to small, fast-burning particles, which is why this mechanism is the correct description.