Loop detectors operate on the principle of which of the following?

Loop detectors operate on the principle of inductance. These devices are used extensively in traffic control systems to detect the presence of vehicles at intersections, in traffic queues, or as they approach traffic signals.

The loop is formed by a wire that is installed in a rectangular or circular pattern in the pavement. When a vehicle, which can be thought of as a mass of metal, passes over or stops above the loop, it affects the magnetic field around the loop. This change in magnetic field induces a change in inductance, which the loop detector is designed to sense. The detector interprets this change as a signal indicating the presence of a vehicle.

Understanding this principle is crucial for traffic signal technicians as it helps in troubleshooting and maintaining these detection systems effectively. By recognizing that the operation relies on electromagnetic induction, technicians can better comprehend how they should set up, test, and respond to the output of loop detectors in the field.