The first metal detector was created in 1881 by Alexander Graham Bell to detect the bullet lodged in the body of President James Garfield when he was assassinated. The first portable version was patented in 1931 by Fischer. Since then, this instrument has become very common. Here are some insights on the workings of metal detectors.

What is a metal detector?
An electronic instrument that can find any instance of metal from the ground, a human body or a parcel is called metal detector. It has the ability to pass through the sand, soil, wood and any other non-metallic items. It can track anything metallic.

How the metal detector is constructed?
An elementary metal detector has an electronic box along with a battery on one side, with a handle to let the operator place his arm. It has a coil made of insulated wire wrapped around the telescoping shaft and ends in a round plastic disk. The disk is displaced from the shaft making an angle that helps it to maintain parallel position to the floor. The operator holds the electronic box and switches on the power to start sweeping the coil slowly on the ground till there is an electronic signal. This signal shows the presence of a metallic item underneath the area already swept by the coil.

How does a metal detector work?
Metal detectors use the principal of electromagnetism and the effect it exerts on metals. The metal coil called the transmitter works on the battery power and generates a magnetic field that works on the surroundings. When this field enters the ground, any metallic item becomes magnetic. This generates the electronic signal, which is detected by the receiver in the coil. Receiver in turn dispatches a signal to the electronic box. The speaker makes this sound louder, generating a beep for the operator. The electronic box consists of microprocessors to measure the time lag between charging the area and receiving the signal. This time lag is called the phase shift and lets you know which metals are present. Using this principle, you can configure the high-end metal detectors to look out for specific metals.