Basics September 12, 2015 ChrisK No comments

How Does Metal Detector Work?

Initially, metal detectors were invented by US President J. A. Garfield in 1881. He was shot by a bullet which entered in his body and went missing. Since then, they have been used by many people for various purposes. Today, they are used for security, industrial, and hobby purposes.

How Does It Work?

How Does Metal Detector WorkMetal detectors use electromagnetism force in order to detect and notify on the presence and location of a metal item. According to James Clerk Maxwell, electricity and magnetism fields are operated in a similar way. Therefore, changing one field translates into changes on the other field too.

A metal detector is made of different parts. These include: handle, transmitter coil, receiver coil, loudspeaker, circular head, and detector plate. The flow of the magnetic and electric current in the transmitter as well as the receiver coils aids in the detection of metals and other materials from the ground or other surfaces.

The transmitter coil is made up of a wire coil that extends from the circular head up to the base. This coil harnesses electricity current from the battery which is normally fitted below the handle. The flow of electric current in the transmitter coil creates a magnetic field move as you move the metal detector from side to side.

How Does Metal Detector WorkThe magnetic field create has a significant effect on the atoms of the metal on the ground. It affects the movement of the atoms/electrons in a metal or item that is hidden or lost on the ground or grass.

According to J. C. Maxwell, movement of electricity current in a metal on the ground creates a magnetic force of attraction. On the other hand, another wire coil known as the receiver coil responds to the electricity flow from the battery by triggering the loudspeaker to beep or vibrate. This indicates the presence of a metal on a surface.

Thus, creation of the magnetic field in the atoms of a metal by the transmitter coil triggers the back-reaction by the receiver coil which, in turn, triggers the loudspeaker to beep or vibrate. There is your metal or valuable item!

Which Factors Affect the Functionality of a Metal Detector?

1. Distance

The closer the transmitter coil is to a metallic object, the stronger the field of magnetism that is created. This increases the chances of faster and more accurate signaling. This makes metal detection accurate and effective.

2. Battery Power

How Does Metal Detector WorkStronger batteries with a longer serving duration enhance metal detection process for a longer period of time. The battery is used to induce the electrical power used for various functions such as: LED light emission, functionality of the loudspeaker, vibrator, transmitter coil, and the receiver coil. Normally, metal detector batteries lasts for over 60 hours of consistent usage.

3. Amount of Current Flowing to the Receiver Coil

More the current flow into the receiver coil leads to more noise or vibration which is produced by the loudspeaker system. As you move closer move closer to where a metal is located, the noise or signaling intensifies. At the same time, old and corroded metals may emit lesser current to the receiver coil than new and non-corroded metals.


Metal detectors have been effectively used in fields such as: industries, security, and military. Through the electromagnetism relationship that is created between the metal detector and a metal on the ground, it becomes easy to find hidden, lost, or discovery metals or items from different surfaces.