Visible products of combustion are best detected by a/an __________ detector.

Visible products of combustion, such as smoke, are primarily detected by a photoelectric detector. Photoelectric detectors work based on the principle of light scattering. When smoke particles enter the sensing chamber, they scatter the light beam emitted by the detector. This scattering of light can trigger an alarm, making photoelectric detectors particularly effective for detecting smoldering fires that produce significant amounts of smoke.

While ionization detectors are excellent for detecting fast-flaming fires, they rely on changes in ionization levels within the air rather than directly responding to visible products of combustion. Ultraviolet detectors are typically used to detect flames, particularly from gas fires, but they do not respond to smoke. Infrared detectors can also be effective in identifying heat and flames but are not specifically designed for smoke detection. Therefore, the photoelectric detector is the optimal choice for accurately and effectively detecting visible products of combustion.