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| 1. |
At an airport, a person is made to walk through the doorway of a metal detector, for security reasons. If she/he is carrying anything made of metal, the metal detector emits a sound. On what principle does this detector work ? |
| Answer» Solution :The METAL detector works on the principle of resonance in ac circuits. When you walk through a metal detector, you are, in fact, walking through a coil of many turns. The coil is connected to a CAPACITOR tuned so that the circuit is in resonance. When you walk through with metal in your pocket, the impedance of the circuit CHANGES – resulting in significant CHANGE in current in the circuit. This change in current is detected and the electronic circuitry causes a SOUND to be emitted as an alarm. | |