A metal detector is an instrument that detects any kind of metal around. Using them, metals found in the ground and other hidden objects are easily noticed. The metal detector has a handled most of the time with a sensor which may be passed on the ground or other material. The presence of a metal is marked by a change in the tone of the earphones. The closer the metal the higher the earphones tone and this tonal variation can tell the distance from where the metal could be found. There is another type of metal detector that you just walk through it. This kind of metal detector is used for security screening at some places like in the airports and courts to detect any kind forbidden weapons that might be carried by people.
What do metal detectors consist
A simple metal detector is made up an oscillator that generates alternating current. The current passes via a coil and releases magnetic field.
History of metal detectors
A metal detector was first constructed in the 196os whose work by then was mineral prospection and other uses in the industry. The uses it carried out were as follows;
- Detect land mines.
- Detect weapons like guns and knives mostly in airports.
- Prospection in geophysics.
- Used in archeology.
- Used for treasure hunting.
- Detect presence of foreign bodies in food.
- Detection the steel reinforcing bars in floors.
How metal detectors were adopted for security screening.
Following increased cases of the hijack of its aircraft, the United States adopted the technology of screening the airline passengers in 1972.
Features of metal detector
Technology of the coil
It is the most important part of the metal detector which sends magnetic field underground to magnetize the metal objects which makes the objects to be detected by the recipient. Two types of coil technology are used and they include;
Very Low-Frequency coil metal detectors
It is the most adaptable as it can be on land and shallow waters. Many of the metal detectors use this technology. Its mono-frequency metal detector uses one fixed functioning frequency and dual frequency metal detectors of this kind use multiple frequencies this is determined by the metal being searched.
The pulse induction metal detector
These metal detectors are less common. They are used for detection in the deep field and deep waters. Normal they don't detect small pieces of gold and other ground interference. This makes them he used mainly in the soils that have a high content of minerals as the detector cannot be confused by the extraneous metals easily
- The size of the coil
How deep a metal detector can search is depended on the search coil diameter. A large coil leads to a great field being detected and a small coil will result to small field detection. Again the size of the coil will determine the size of the object that is detected. With a large coil, it easily misses small metal pieces. But on the hand, small coil is very effective in detecting fragments of debris and small pieces of metal. Large coils can detect very well large metals.
- The target identification feature
It is used to identify the metal object which has been identified. it leaves the operator with the decision of dig the metal detected or not. Target identification is made up of the following categories of identity; dimes, quarters and a half dollars to identify copper pennies, iron, foil, nickel and other items which are similar. In some detectors, this feature is programmed to detect specific objects or metals.
- The tone of identification
A certain number at metal detectors produce varying tones of sound as per to the metal that has been detected. An example is like those objects that are composed of iron, nickel, and full produces low sounds and screw caps results to the emission of medium sound. But objects consisting of gold produce high sound.
- Operating in multiple modes
You find some metal detector that works more than one mode, the common modes are;
- Detection of all metals
Here there is the detection of all metals. if offers the greatest detection ability.
- Mode of full discrimination
In this mode, most trash items are rejected automatically.
- Mode to discriminate the tone
The metal detector produces different sounds for different metals and objects. Like broken tone for the presence of pull-tabs and this makes it easy to search for treasures.
- The mode of pinpointing
This involves the aligning of any detected objects according to the center or search coil distance. with this mode, the operator can accurately locate the targeted object easily.
Controversy about metal detectors
- Educators and lawmakers have argued out that it takes long to screen a large crowd of students in a school.
- It is also argued that how many professionals shall be needed in order to run screening effectively.
- The question of how often metal detectors are supposed to be used in schools.
Pros of metal detectors
Prevention of violence occurrence
Like in schools in the past violence have been recorded involving knives and guns. But since the introduction of metal detectors at the main entrances, there has been a reduction in weapons among students hence decreased violence in these institutions.
Detection of weapons
In schools and colleges, the gang activities of students have been the cause of carrying weapons in schools for to bully others. With the metal detectors in place, these weapons are detected and taken this ensures there is conducive learning environment in schools.
The experience of tardiness
Metal detectors are used every place a large crowd by the guards who do through screening hence ensuring the people are as safe as possible.
Cons of metal detectors
Metal detectors expensive
It is expensive to acquire and maintain a metal detector. It may sometimes require trained personnel to handle it.
Myths of metal detectors
- Metals make a lot of noise.
- The metal detectors are depended on X-ray technology.
- Metal detectors can be used everywhere.
- Those who find valuables by using metal detectors are the experts only.
Metal detectors are the course that is to be embraced to ensure security all the time.