The working of the hand-held metal detector most widely used by security personnel for human frisking is based on the principle of:
Show Hint
- Change in reluctance of an iron core in presence of a metallic object
- Change in conductance of an iron core in presence of a metallic object
- Electric field induced by a metallic object
- Eddy current generation in a metallic object
The Correct Option is D
Solution and Explanation
Hand-held metal detectors operate on the principle of electromagnetic induction. When the device is moved over a metallic object, it induces eddy currents in the metal.
Step 2: Effect of eddy currents.
These eddy currents generate their own magnetic field, which interferes with the original magnetic field of the detector’s coil. This interference is detected as a change, indicating the presence of metal.
Step 3: Conclusion.
This is not about changes in reluctance or conductance, nor electric fields. It's based on magnetic field disturbance due to eddy currents.
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