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Many homeowners concerned about security install motion detectors on their property to deter would-be burglars and other intruders. They are also sometimes used to monitor the activities of children and pets. 

Motion detectors can be quite complicated systems, but are used more or less the same way in home security situations. Outside the home, the motion sensor is usually hooked up to a camera or flood lights, which come on when the sensor detects motion. Inside the home, motion sensors can be connected to windows or doors with alarms that sound if the sensor detects movement. They can also contact your smart phone or local law enforcement. 

Here are two types of motion detectors commonly used in home security systems. 

Passive Infrared Detectors 

Passive infrared systems are the most commonly used by homeowners because they’re reliable and affordable. They work by detecting changes in temperatures in a given area. Passive infrared sensors do not emit energy of their own. 

Active Motion Detectors 

Active infrared sensors, on the other hand, use optics, sound waves or radiation to detect motion.  The main difference between passive infrared detectors and active motion detectors is that active detectors emit some sort of energy; passive detectors do not. Active motion sensors are often used in commercial settings to open doors or ring bells whenever someone approaches the threshold. 

Motion detectors are not completely foolproof when it comes to catching intruders. They can have gaps in their coverage, and can sometimes be blocked by radio signals or light waves. In any case, it’s important to consult a home security specialist if you have any doubts.