Aloop of wire embedded in the road at an intersection can be used to trigger a traffic signal. this is an application of magnetic induction. explain

A loop of wire installed at an intersection can be used to trigger a traffic signal.

Explanation:

Electromagnetic induction has an application in the field of vehicle detection. It can be used to detect vehicles crossing a point, like a traffic signal. Detection is achieved by placing an electrically conducting well insulated loop at the required point.

Alternating currents of appropriate frequency are passed through the loop and the system becomes a tuned electrical circuit. Passage of a vehicle through the loop increases its inductance. This change is due to the ferrous components of the vehicle.

The vehicle being a metallic body causes eddy currents to develop within the loop. This brings a decrease  in  the inductance of the loop. Increase in inductance when compared with the decrease is visibly great.

This produces an overall decrease in inductance of the loop which reduces the impedance of the circuit to alternating current. This triggers the development of a pulse to traffic signal controller indicating the passage of  a vehicle.

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