Question

Which of the following are correct about metal detector?

• A. It uses an electromagnet.
• B. It uses a permanent magnet.
• C. Magnetic field is detected by the metal detector.
• D. It is capable of detecting few non - metallic objects too.

Answer 1

Answer: (A), (C)

The correct options are
A It uses an electromagnet.
C Magnetic field is detected by the metal detector.

A metal detector incorporates an electromagnet within it for screening purpose and detection of concealed weapons. The electromagnet once powered, emits magnetic field onto the metal which is to be detected which inturn generates a magnetic field of its own and is received by the metal detector. Permanent magnets cannot be used in this application since it cannot generate strong magnetic fields and may cause unnecessary problem because its attractive property cannot be deactivated. Non metals cannot generate field by induction and hence cannot be detected by metal detectors.