Metal detector
A metal detector is a tool a person can use to help find metal nearby. It is useful for finding metal within other objects, or for finding metal underground. Most metal detectors will make a sound or have a needle move on a sensor in order to show where objects are. This tells how close you are to an object - for example, by making a higher-pitched sound when you are closer to an object.
History of the metal detector
Alexander Graham Bell invented a kind of metal detector in 1881 when he was trying to find the bullet in President James Garfield’s body after he had been shot. The metal detector worked but it was confused between the bullet and a coiled bed-spring on which the President lay.
Gerhard Fischer made a better version in the 1920s but the detector got confused when someone was approaching ore-bearing rocks. He was given a patent in 1925. A businessman named Shirl Herr had earlier tried to get a patent for a metal detector but was not given one until 1928.
Uses
A metal detector can be used by archaeologists for finding things like metallic coins, bullets, and jewellery underneath or inside a surface.
Written for younger readers
Metal detector, in simpler words
This version comes from Wikijunior, a set of books written for children aged 8 to 11. It is shorter and uses plainer language than the article above.
From Wikijunior: How Things Work
In the late 1800s, many scientists and engineers used their knowledge of electricity to try to invent a machine which would find metal. It could be used to find valuable stones, so it could make a lot of money. The German physicist Heinrich Wilhelm Dove invented the basics for the metal detector, which was made into a metal detector a hundred years later. Early machines were sloppy and used a lot of battery power, and worked for a very short distance. Better versions of the metal detector started to be created in the 1930s.
A scientist named Gerhard Fischer wanted to find a way to know where you are and what direction you are going. It is similar to today’s GPS (Global Positioning System). It worked really well, but Dr. Fischer noticed that there were problems in places where the ground had rocks with ore in them (ore is rock that contains metal). He found out that this could be used to find metal. In 1937, he got the first patent for a metal detector. His designs were used as mine detectors during the Second World War (mines are bombs that are hidden underground). The metal detectors were heavy, had vacuum tubes, and needed separate battery packs. After the war, there were plenty of leftover mine detectors on the market. They were bought up by treasure hunters who used them for fun and for gaining money. The hobby of metal detecting had been born.
Usually by battery.
The transmitter coil and the receiver coil.
It can be used to search for valuable stones and artefacts. It can also be used to find mines and to use as security systems. For example, if someone is carrying a metal gun or bomb a metal detector can find it (although if the bomb is sensitive to magnetism it could cause the bomb to explode instead.) Some kinds of metal detectors can tell what kind of metal is being found and how far away it is.
Metal detectors use one of three technologies:
Very low frequency (VLF) Pulse induction (PI) Beat-frequency oscillation (BFO)
In countries where there have been wars, there are still many mines buried in the ground which continue to injure people. In these regions, metal detectors are the best way to solve the problem and make the areas safe again. They have also been used to make important historical finds.
-The Scottish physicist, Alexander Graham Bell, the inventor of the telephone, used a metal detector to try to find a bullet that was in the back of American President James Garfield in 1881.
Where this page comes from
The article above is adapted from “Metal detector” on Simple English Wikipedia, by its contributors. We removed reference markers, navigation boxes and tables, expanded measurement templates into readable numbers, and kept the prose otherwise intact. The simpler version is adapted from Wikijunior on Wikibooks.
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