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CCSP · Question #150

There are two general types of smoke detectors. Which type uses a small portion of radioactive material?

The correct answer is B. Ionization. Ionization smoke detectors operate by using a small amount of radioactive material to ionize the air between two electrically charged plates, detecting smoke when it disrupts the current.

Submitted by tunde_lagos· Apr 18, 2026Cloud Platform & Infrastructure Security

Question

There are two general types of smoke detectors. Which type uses a small portion of radioactive material?

Options

  • APhotoelectric
  • BIonization
  • CElectron pulse
  • DIntegral field

How the community answered

(38 responses)
  • B
    95% (36)
  • C
    3% (1)
  • D
    3% (1)

Why each option

Ionization smoke detectors operate by using a small amount of radioactive material to ionize the air between two electrically charged plates, detecting smoke when it disrupts the current.

APhotoelectric

Photoelectric smoke detectors work by using a light source and a photosensitive sensor; smoke interferes with the light beam or scatters light into the sensor, triggering the alarm, and do not use radioactive material.

BIonizationCorrect

Ionization smoke detectors contain a small amount of radioactive material, typically Americium-241, which ionizes the air in a chamber between two electrodes, creating a small, constant electric current. When smoke enters the chamber, it disrupts this current, triggering the alarm.

CElectron pulse

Electron pulse is not a standard type of smoke detector.

DIntegral field

Integral field is not a standard type of smoke detector.

Concept tested: Types of smoke detectors

Source: https://www.cpsc.gov/safety-education/safety-guides/home/smoke-alarms

Topics

#Smoke detectors#Physical security#Environmental controls#Ionization detectors

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