A world made of metal


Metal Detectors to Get That Rare Find

The first metal detector was invented bythem. Magnetic field is generated in this
Alexander Graham Bell in the year 1881, justdevice through the transmitter (high-powered
after the invention of telephone in 1876.coil), getting power from the battery
Later, Fischer came out with a portable oneattached. When this electromagnetic field
in the year 1931. Today, metal detectors arepenetrates the ground the metals tend to get
used in many fields starting from treasurecharged with magnetism. When this happens the
hunt to security purposes. These arecoil detects the electromagnetic behaviour
electronic devices and are used to locateand sends a signal to the electronic box. The
signs of metal. It is used to search on thespeaker attached to the electronic box beeps
ground, people or goods. The materials can beand the operator hears it and comes to know
on the ground may be a piece of iron,of the presence of metal. The latest
aluminum, etc or it can even indicate burieddetectors comprises of microprocessors in the
metal could be anything from discarded pieceselectronic box that can give you the type of
of aluminum to buried resources. Thesemetal present. It can measure the time
detectors can penetrate various non-metallicbetween charging of metal and the receiving
substances  like  soil,  wood,  sand,  etc.the beep that concludes the type of metal and
this length of time is known as phase shift.
Metal detectors have electronic boxes with aThere are adjustments in the device when
battery case on one end and a handle for thesearching  for  a  particular  kind of metal.
operative's arm on the other. It has a coil
made of insulated wire wound around aThere are 3 types of metal detectors
telescoping shaft that is inside a plasticfollowing  3  different  technologies:
disk. The device is held parallel to the
ground due to the angle at which the disk1. Beat Frequency Oscillator: Such detectors
comes out of the shaft. The electronic box ishave a coil acting as an inductor inside an
held in the hand, the power is put on and theoscillator. With frequency change there is a
coil end is slowly swept over the ground. Ifchange in inductance. There is a second
the trace of metal is there on or buried inoscillator that generates a close frequency.
the ground, an electronic beep is heard whenThe beeps heard between them indicate the
the  device  sweeps  the  ground.presence  of  metal.
The discovery of Electromagnetism was by Hans2. Induction Balance Detector: This type has
Christian Oersted in the year 1820. It is the2 coils that overlie each other. One sends
science of combined effect of electric andwaves and the other receives. The two are
magnetic field. As stated in wikipedia,kept adjusted so that when there is absence
Electromagnetism is the science of theof  metal  they  do  not  indicate  or  beep.
electromagnetic field. That is, a field,
surrounding all of space, which exerts a3. Pulse Induction Detector: This type
force on those particles that possess theproduces pulses by putting off an indicator.
property of electric charge, and is in turnA coil sends the pulse and the detector
affected by the presence and motion of suchsearches  for  echos.
particles.
If you have a metal detector, I wish you luck
This principle of electromagnetism is onin finding all kinds of treasures. You never
which the Metal detectors work. Since theknow what "rare find" you'll come up with,
metals are good conductor of electricity andand it's fun to look.
magnetism, the electromagnetism affects on



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