Technology
How does a metal detector work?
A metal detector works by sending out a magnetic field that creates tiny electric currents in any nearby metal. Those currents make their own field, which the detector senses and announces with a beep — revealing metal hidden underground or in bags.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a metal detector works.
Step by step
- 1A coil generates a changing magnetic field.
- 2Metal nearby develops small swirling currents ('eddy currents').
- 3Those currents create their own magnetic field.
- 4A second coil detects that returning field and triggers a signal.
- 5Different metals respond differently, helping identify what's found.
Frequently asked questions
- How does a metal detector find metal?
- Its magnetic field induces tiny electric currents in nearby metal, and those currents produce a field the detector senses, setting off the beep.
- Why does a metal detector beep louder near big objects?
- Larger or closer metal produces stronger induced currents and a bigger return signal, so the response is stronger.
- Can a metal detector tell different metals apart?
- Somewhat — metals conduct differently, so the strength and timing of the signal hint at whether it's iron, gold, or aluminum.