7. Specialist Reading: How the Airport Walk-Through Metal Detector Works

As you should know, this Unit was about one security devices used at airports: a walk-through metal detector. It is a device which detects metal objects. It is based on electromagnetism and is full of coils. As future professional electrical engineers, we can assume that you already know something about the technical principle of this security device. Still, read about it in this task. As you read, complete all the gaps in the task.