Metal detector is meant to detect the presence of which of the followi

Metal detector is meant to detect the presence of which of the following in the search object ?

Ferrous metal only
Ferrous and plastic objects only
Ferrous and non-ferrous objects only
Ferrous, non-ferrous and plastic objects
This question was previously asked in
UPSC CISF-AC-EXE – 2022
The correct answer is C) Ferrous and non-ferrous objects only. Standard metal detectors operate by detecting disruptions in an electromagnetic field caused by conductive materials, which include both ferrous metals (containing iron) and non-ferrous metals (like aluminum, copper, gold, silver).
– Metal detectors work on the principle of electromagnetism. They emit an electromagnetic field and detect the presence of metal objects by measuring the secondary magnetic field induced in the object or the change in the primary field.
– Ferrous metals are magnetic (e.g., iron, steel), while non-ferrous metals are not magnetic but are still conductive (e.g., aluminum, copper, brass, gold). Both types interact with the electromagnetic field of a metal detector.
– Plastic is not a conductive material and therefore does not interfere with the electromagnetic field in a way that a standard metal detector can detect.
While standard walk-through and hand-held metal detectors detect metals, other security screening technologies exist to detect non-metallic objects like plastics, ceramics, liquids, or explosives, such as X-ray scanners, body scanners (using millimetre wave or backscatter technology), and trace detection portals.