Final answer:
Dual technology detectors trigger an alarm when smoke disrupts the ionization process between metal plates inside a smoke detector, caused by americium radioactivity.
Step-by-step explanation:
The correct answer is option "Dual technology detectors initiate an alarm upon significant changes in environmental conditions, specifically when smoke from a fire interferes with the ionization process between two metal plates inside a smoke detector.
" This happens because the radioactive element americium within the smoke detector ionizes air particles, allowing a small electric current to flow between the plates. When smoke particles enter the detector, they disrupt this current, leading to a drop in current below a predefined threshold, which triggers the alarm.
The correct answer is option B. Dual technology detectors initiate an alarm upon the interference of smoke particles in the smoke detector's ionization chamber. In an ionization-type smoke detector, two metal plates are placed in an ionizing chamber next to a small disk containing a tiny amount of the radioactive element americium.
The radioactivity of americium ionizes the air between the plates, causing a constant current to flow. When smoke particles enter the chamber, they disrupt the ions, resulting in a drop in current, which triggers the alarm.