Question

When you walk through a metal detector carrying a metal object in your pocket, it raises an alarm. This phenomenon works on:

• A. Electromagnetic induction
• B. Resonance in ac circuits
• C. Mutual induction in ac circuits
• D. Interference of electromagnetic waves

Hint:

Metal detectors work on the principle of resonance. When a metal object resonates with the electromagnetic field, it causes a change that triggers the alarm.

Answer 1

The Correct Option is B

Step 1: Metal detectors typically work on the principle of resonance. When a metal object is passed near the detector, it alters the frequency of the electromagnetic field inside the detector. 
Step 2: The metal object resonates with the frequency of the electromagnetic waves generated by the detector, which causes a change in the oscillation and triggers the alarm. 
Step 3: Hence, the phenomenon works based on resonance in AC circuits, where the resonating metal object causes a disruption in the frequency of the electromagnetic waves.