Visible products of combustion are best detected by a/an _________ detector:

A photoelectric detector is designed to detect visible products of combustion, such as smoke, through the use of a light source and a light-sensitive sensor. When smoke particles enter the detection chamber, they scatter light, causing a change in the light intensity that is registered by the sensor. This makes photoelectric detectors particularly effective for detecting smoldering fires, which produce larger particles of smoke and might not ignite as quickly as flames.

In contrast, ionization detectors operate by using a small amount of radioactive material to ionize the air in a sensing chamber. They are more responsive to fast-flaming fires that produce smaller combustion particles, rather than visible smoke. Ultraviolet detectors are primarily designed to detect flames directly, while infrared detectors can sense heat or flame but are not specifically optimized for detecting smoke. Therefore, for situations where visible products of combustion are present, the photoelectric detector is the most suitable option.