Members Login
Username 
 
Password 
    Remember Me  
Chatbox
Please login or register to participate in the chat
djromie (Mzja Dj) wrote
December 31st
sayhello blessed new year
 
tallboss876 wrote
November 16th
hail
 
djromie (Mzja Dj) wrote
October 15th
anyone dehya
 
djromie (Mzja Dj) wrote
October 15th
csmi di ting up like7 again sayhello
 
Mediiazone Forums → MZ @ 2013 :: A Owa Endz → News & Topical Issues → Metal detectors use electromagnetic induction to detect metal pt 1
 

Topic: Metal detectors use electromagnetic induction to detect metal pt 1

Page 1 of 1  sorted by
Wide (rest of width)
Narrow (200px)
dj rushie
MZ Teacha
Status: Offline
Posts: 814
Date:

Metal detectors use electromagnetic induction to detect metal pt 1
Permalink  

Metal detectors use electromagnetic induction to detect metal. Uses include de-mining (the detection of land mines), the detection of weapons such as knives and guns, especially at airports, geophysical prospecting, archaeology and treasure hunting. Metal detectors are also used to detect foreign bodies in food, and in the construction industry to detect steel reinforcing bars in concrete and pipes and wires buried in walls and floors.

In its simplest form, a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field. If a piece of electrically conductive metal is close to the coil, eddy currents will be induced in the metal, and this produces an alternating magnetic field of its own. If another coil is used to measure the magnetic field (acting as a magnetometer), the change in the magnetic field due to the metallic object can be detected.

 

Toward the end of the 19th century, many scientists and engineers used their growing knowledge of electrical theory in an attempt to devise a machine which would pinpoint metal. The use of such a device to find ore-bearing rocks would give a huge advantage to any miner who employed it. The German physicist Heinrich Wilhelm Dove invented the induction balance system, which was incorporated into metal detectors a hundred years later. Early machines were crude, used a lot of battery power, and worked only to a very limited degree. Alexander Graham Bell used such a device to attempt to locate a bullet lodged in the chest of American President James Garfield in 1881; the attempt was unsuccessful because the metal bed Garfield was lying on confused the detector.[1]Advantages and disadvantages of metal detectorsSome advantages of security metal detectors are:
  • The immediate and most obvious advantage of metal detectors is enhanced office security.
  • They play a very important role in preventing workplace violence by picking out persons bringing in weapons to an office.
  • They help in pilferage prevention, especially of precious metals.
  • Hand-held body scanners for body search eliminate the need for physical pat-downs during weapon screening, avoiding embarra**ment to clients/ employees.
Some disadvantages of metal detectors could be:
  • They may sometimes give a false alarm if someone is carrying even harmless metallic objects (e.g. toys), or say gold jewelry/coins as a personal belonging, causing a lot of embarra**ment and inconvenience to the person.
  • They may not always be safe for people fitted with a pacemaker.
  • They may interfere with magnetic recording media like cassettes and CDs.

 

 

Adults, not metal detectors, are what schools need, says Nicki Mason

Carrying a knife is never a good idea when not on a camping trip. Most children learn this easily at an early age outside school and often without discussing it. Circumstances lead them to discover it is good to be alive, and they begin to value their own and others lives. For the majority of schools therefore, knife crime is absolutely not a problem, and knives feature only on the long list of items not allowed in school, along with drugs, alcohol, fireworks, chewing gum and dangly earrings.

Not all children hear the message, however, and a small minority of schools do have to deal with incidents involving knives and the circumstances surrounding them. In my experience the young person who carries a weapon does it for their own 'protection' because they feel threatened. Few have given any consideration to the most likely outcome of a confrontation - that a person or group of people bigger and stronger than them take it and use it against them. Once this is brought to their attention by an adult it is often enough to change their behaviour on the spot.

Children are capable of reason. Introducing metal detectors is to abandon reason and to send the wrong messages:
  • A metal detector at the school gate says it is acceptable to carry a knife on the street.
  • A metal detector at the classroom door says it is acceptable to carry one in the corridor.
They do not teach that carrying a knife is never a good idea, and is likely to lead to crime or death. Metal detectors do not change behaviour. Inspirational and passionate teaching of subjects, together with consistent enforcement of clearly expressed rules and discussion of reason, does. Young people are guided by the adults around them. They are inspired by adults who take a genuine interest in

__________________

Nico-T
"THE INFAMOUS NICO-T"
Status: Offline
Posts: 10119
Date:
Permalink  
***NICO-T SPEAKZ***



hmm AAAH

__________________



Page 1 of 1  sorted by
Quick Reply

Please log in to post quick replies.
 
Tweet this page Post to Digg Post to Del.icio.us