The History of Metal Detectors
Metal Detectors have a very unique past as they have evolved over the years as an important piece of history. Earlier versions of what we know today that includes modern technology were first developed back in the late 1800s. At this time, a crude metal detector was made quickly in an attempt to save President James Garfield from a gunshot wound that later took his life. But, the electromagnetic concept would soon be perfected into a useful well known device.
The People behind the Metal Detector
Alexander Graham Bell was behind the first metal detector around 1881. He tried to come up with a metal detector in a frantic attempt to save President Garfield from a bullet wound. Soon after, Bell recognized the metal coils in the bed President Garfield was laying on affected his attempt in saving the president. It caused what he called an induction balance from his electromagnetic device.
A German physicist named Heinrich Wilhelm Dove worked with the device and developed the theory of magnetism. During this time, other scientists were working on concepts that would detect different types of metals. In 1925 the first hand-held metal detector was developed by inventor Gerhard Fischer. By the 1930s it was patented and available for commercial sale. Later, metal detector manufacturers designed lighter and smaller detector devices that ran on batteries during the 1950s and 1960s.
What Do They Detect?
Jewelry, coins, minerals, and other objects can be detected at different depths in soil or water. Such magnetic fields are able to penetrate layers to pick up a metallic signal that the device picks up. Their frequencies are measured in kilohertz or kHz. A large number of objects with metallic material can be picked up by metal detectors such as lead, gold, brass, aluminum, silver, nickel and iron.
Metal Detectors in Modern Society
There are various types of metal detectors and their designs and purposes vary. They feature low and high frequencies while having the ability to detect different kinds of metals. Some use computer technology to determine volume, parameters, and other aspects of magnetic detection. Five main types of detectors are available and are developed for different purposes. Some detect metals in the ground, water and on land. Some of the more common types of metal detectors are used to detect weapons at building entrances such as schools, airports, and courthouses.
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