Ever felt frustrated when one time you walked into an airport and guards frisk your belongings? Did you notice the gadget they used to scan you from top to bottom? Then when the gadget passed over your pockets it made a loud stinging sound. You discovered that it was because of your phone or coins. Well, the gadgets that are usually used is referred to as metal detectors. What is a metal detector? According to Wikipedia.com and encyclopaedia.com, metal detectors are an electronic instrument which detects metals nearby. Metal detectors help to reveal metal substances which are covered within the ground, human body, the sea and many other places. How do they work? There are ( detectorly.com) different types of metal detectors. They work in different ways. However, the science behind a basic metal detector is electromagnetism. Electromagnetism is the connection between magnetism and electricity whereby if you wrap a coil of wire around a metal rod, and connect it to a battery then you will create an electromagnetic field. An electromagnetic field is a field produced by objects that are charged electrically (Mirza, 2011). Basically, it means producing electric currents using magnetism. A metal detector has a coil of wire wrapped around a rod known as the transmitter coil. As electricity is passed through the coil, a magnetic field is created. When a person moves the metal detector over an area or platform e.g. the ground or someone's pockets, the field moves with it. Consequently, when the detector comes close to a metal it induces a magnetic field around the metal because of the electric current it bears. This second magnetic field is the one that the detector picks up. The detector has a receiver coil which is connected to a speaker. Therefore, when the second magnetic field cuts through the coil, electricity is produced and the speaker beeps or clicks. It is important to note that the closer the detector moves to the metal, the stronger the magnetic field. This translates to louder sounds. Therefore, the closer the detector comes to the metal, the louder the noise (Woodford, 2016). Metal detectors work in two modes: Active and Passive. a. The active detection comes to play when there is a detection space like someone's hands. The presence of a metal interrupts the flow of energy reflected in the particular space. The metal detector indicates the presence of a metal by calibrating these effects. b. The passive detection works in unshielded spaces which already contain the earth's magnetic field. For instance, the ground. if there is a ferromagnetic object like a metal, it causes detectable changes to the fields (Woodford, 2016]. Types and uses of metal detectors The uses of different metal detectors are determined by their types. Here are their types: 1. Walk-through metal detectors- Also referred to as portal detectors are most common in airports and military facilities. They have two large coils. A source and the other one detects. The source generates an electromagnetic field which, if it interacts with a conductor it generates electromagnetic forces on the surface of the object. The object radiates electromagnetic waves in turn which are received by the detector (Gilman, 2016). 2. Hand-carried metal detectors- These are more common at security checkpoints since they are small and can be carried by the hand. They work under the same principle of the walk-through detector. Some can be installed on a pedestrian scanning so that they may detect metallic objects in the soil. 3. Gradiometer Metal Detectors- These detectors are used as passive detectors to detect ferromagnetic objects. They can be mounted on police vehicles to detect ferromagnetic weapons when they come near anyone who has it. 4. Magnetic imaging portals- These illuminate a detectable space through radio-frequency electromagnetic waves through several small antennas arranged around the portal, pointing inward. When in the presence of a conductor they compute a sketchy image of the object in the portal. History of Metal Detectors The first metal detector was invented by Alexander Graham Bell in order to save President James Garfield. He had been shot in Washington D.C in July 1881 but the bullet could not be found. Alexander invented the metal detector with the intention of finding the bullet but unfortunately, the bullet was never found. President Garfield later died in September 1881. However, the technology got developed by Gerhard Fisher who made the first portable metal detector. Metal detectors were also used in World War l and all to detect and clear landmines and also find unexploded bomb across Europe. Advantages of Metal detectors 1. Metal detectors have been very instrumental in enhancing security. Due to their scientific accuracy, they are able to detect weapons such as guns, knives etc that could be used to harm people. They were also used to detect bombs hidden in the ground in World Wars l and i. 2. Metal detectors have also been used to discover metallic minerals which have been buried deep in the ground. 3. Metal Detectors have also been used to find precious metals in the sea. 4. Ever heard of the phrase needle in a haystack? A metal detector can help a person find the needle. They can be very instrumental in finding lost metallic objects such as coins and jewelry. 5. Metal detectors have been used to find meteorites in the earth. Myths about Metal Detectors debunked. 1. Metal Detectors are not safe- The truth is the amount of radiation that is emitted is safe for everybody including pregnant women and children. This has been proved by the National Institute of Standards and Technology (NIST) at the John Hopkins University. 2. Metal detectors are not correct always- The metal detector technology is very effective such that the electromagnetic fields can detect any kind of metal that passes through. Tips when buying a metal detector 1. First, find a metal detector that well suits your needs. Having known about the various types. 2. Experts recommend that one buys from established brands. You need to google the trusted brands of quality metal detectors.
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