What does ldr sensor work in fire alarm?

An LDR (Light Dependent Resistor) sensor in a fire alarm detects changes in light levels, typically caused by the presence of smoke or flames. When a fire occurs, it can produce a significant amount of light, which the LDR senses by decreasing its resistance and triggering an alarm. This allows the fire alarm system to respond quickly to potential fire situations by alerting occupants and emergency services. However, LDR sensors are often used in combination with other types of sensors, such as smoke or heat detectors, for more reliable fire detection.