Ok, so here's the question...
At the security area of an airport, you walk through a weak AC magnetic field inside a lare coil of wire. So then what is the result of a small piece of metal on your person that slightly alters the magnetic field in the coil?
2006-10-01 07:15:48 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Physics
The presence of a certain materials in a coil alters the coil's inductance, or resistance to the flow of electrons. Most metals, especially those containing iron, and some ceramics will cause this effect as the atoms in the material resist the magnetic flux. In other words, the changing magnetic field tries to alter the orientation of the atoms in the metal which are like little magnets themselves. The atoms resist this change, making it harder for electrons to flow in the coil. The coil is a part of oscillator circuit, and changing the inductance changes the frequency of oscillation. The output of the oscillator is compared to a reference in a phase-lock-loop circuit, which detects changes in frequency.
2006-10-01 07:49:36 · answer #1 · answered by ann_tracks 2 · 0⤊ 0⤋
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2016-12-26 06:32:57 · answer #2 · answered by ? 3 · 0⤊ 0⤋
Well, it depends upon the Sensitivity setting of the metal detector. As it is clear, the threshold value of the metal detector's sensitivity can be adjusted to suit various needs.
so it is obviously set to discard small variations caused by a very small pieces of metal.
2006-10-01 08:35:30 · answer #3 · answered by Anonymous · 0⤊ 0⤋
The metal creates a small variation in the field which the detector can sense.
2006-10-01 07:19:19 · answer #4 · answered by bruinfan 7 · 0⤊ 0⤋
You ought to see me go through one..I have a prosthetic left leg made of titanium, aluminum and carbon, and I have a cardiac defibrillator..the security guys just kinda shake thier heads
2006-10-01 07:25:21 · answer #5 · answered by Anonymous · 0⤊ 0⤋