How does a photoelectric smoke detector primarily function?

A photoelectric smoke detector primarily functions by measuring the amount of light under specific conditions. This type of detector uses a light source, usually a light-emitting diode (LED), and a photosensitive sensor placed within a sensing chamber. Normally, the light emitted by the LED does not strike the sensor directly. However, when smoke particles enter the chamber, they scatter the light, redirecting some of it towards the sensor.

As the concentration of smoke particles increases, more light is scattered and detected by the photosensitive sensor, which triggers the alarm. This method is particularly effective in detecting smoldering fires, which produce larger particles of smoke that can scatter the light more effectively than other types of smoke detectors, such as ionization detectors that respond more rapidly to flaming fires.

The incorrect options focus on different mechanisms that do not characterize the functioning of photoelectric smoke detectors. While temperature changes can indicate a fire, this is not the principle behind photoelectric detection. Dust evaluation does not correlate closely to smoke detection, as dust particles do not necessarily affect light scattering in the same way smoke does. Sound wave analysis is irrelevant to the operation of smoke detectors, as they do not rely on auditory signals but rather on changes in light intensity caused by the presence of