Which item below would NOT be considered a non-intrusive detection device?

Non-intrusive detection devices are those that do not physically interfere with the environment they monitor. They can gather information without altering the physical state of the area or object.

Photoelectric sensors utilize light-beam breaks to detect movement or the presence of objects, making them non-intrusive since they require no physical contact with the detected object. Video cameras capture visual information without needing to touch the subject or area being monitored. Inductive loops work by detecting changes in electromagnetic fields when vehicles pass over them; while they are typically embedded in pavements, they operate based on the presence of vehicles without needing to penetrate deeper into the surrounding environment.

Magnet detectors, on the other hand, generally require some form of physical interaction with the environment. They typically rely on the magnetic field generated by objects, such as vehicles, and often necessitate placement or installation that can alter the surrounding area, making them more intrusive compared to the other options provided. Thus, magnet detectors would not be considered a non-intrusive detection device.