Metal detector vs lead?

[Dosproduction]

So there was a post regarding the shed aquarium and security. So I was wondering if lead stops metal detector.

 

[Frank_N_Stein]

Lead stops x-rays from penetrating the body. I don't believe lead would defeat a metal detector because lead is a metal. But I'm not a scientist so I really have no idea.

 

[BehindBlueI's]

All a metal detector does is notice changes in it's magnetic field due to the presence of metal. So, no.

 

[Mark 1911]

All a metal detector does is notice changes in it's magnetic field due to the presence of metal. So, no.

So metal detectors only detect magnetic metals, not non-magnetic?

 

[T.Lex]

What about porcelain?

I'm familiar with some... specific intelligence sources that say certain modern porcelain can make a firearm invisible to metal detectors.

 

[cosermann]

All you need is a magnetic cloaking device. Problem solved.

 

[BehindBlueI's]

So metal detectors only detect magnetic metals, not non-magnetic?

No. Aluminum isn't magnetic in the "sticks to iron" sense, but creates a disturbance in the electro-magnetic field the detector generates, and the disturbance is actually what the detector reacts to.

I honestly don't understand the underlying physics well enough to know why it works, but that's how it works.

 

[Kirk Freeman]

Induction, electromagnetic induction to be precise, is the term you are hunting for.

*rubs forehead*

Why are you asking, Dos? I gots to know.

 

[Mark 1911]

No. Aluminum isn't magnetic in the "sticks to iron" sense, but creates a disturbance in the electro-magnetic field the detector generates, and the disturbance is actually what the detector reacts to.

I honestly don't understand the underlying physics well enough to know why it works, but that's how it works.

Me either. But very interesting just the same. Never knew that before.

 

[Thor]

Induction, electromagnetic induction to be precise, is the term you are hunting for.

*rubs forehead*

Why are you asking, Dos? I gots to know.

 

[Mark 1911]

Never thought about this before but it's the same principle behind traffic lights that trigger based on a car pulling up to the light. Electromagnetic coupling, when the steel wheel couples with the magnetic field.

Some of these traffic lights used to give me fits back in motorcycle days. The aluminum wheels on the Goldwing would not trigger the traffic lights. Good thing BBI or Kutnupe14 were not around to see how I dealt with those situations.

 

[HoughMade]

You thought all those guys on the beach with metal detectors were going after what? Car keys? The car?

https://www.explainthatstuff.com/metaldetectors.html

 

[chezuki]

What about porcelain?

I'm familiar with some... specific intelligence sources that say certain modern porcelain can make a firearm invisible to metal detectors.

Yeah, but it costs more than you make in a month.

 

[Tactically Fat]

Also note: It doesn't even have to be metal/metallic to set off a metal detector. Carbon fiber "devices" can also trigger them. Your CF "letter opener" is NOT guaranteed to make it through a metal detector without being detected.

 

[Thor]

Let alone a body scanner...you will not get through with anything dangerous.

 

[russc2542]

All you need is a magnetic cloaking device. Problem solved.

you jest but I walked through 7 metal detectors as a scout with a 2" folding knife forgotten in my pocket (plus belt, shoes, jeans rivets, etc) when we visited DC late 90s or 2000. not a peep out of them.

Scout master not so much... they didn't quite strip him but they did thoroughly pat him down in his shorts and undershirt a few times. no artificial joints or implants, just the rivets in his jeans, button on his cap, eyelets on his shoes... they finally waved him through even though it was screaming giving him the benefit of the doubt because we were a boy scout troop.

 

[Drail]

Whether or not it is detected depends on how much metal, it's size and shape and most importantly how low the sensitivity on the machine is turned down to. There are no guarantees what will or won't make it through without setting off the machine. I used to work in manufacturing and we had metal detectors set up at the doors because employees were walking out with parts and small precision tools. We experimented a lot with settings and it was easy to go from "detects everything" to "doesn't detect much". It was pretty much a joke. If we turned it to high sensitivity everyone's cell phone or lighter set it off and we had to stop and search them. There isn't much metal in a cell phone or a BIC lighter. One night a maintenance guy with a tool belt walked through but didn't trigger the alarm. HUH? Management always wanted us to set the sensitivity on low to keep the line moving but that meant we were missing a lot of stuff.

 

[cosermann]

So metal detectors only detect magnetic metals, not non-magnetic?

Any material that can induce an eddy current in a magnetic field can be detected by a metal detector (including carbon fiber).

Here's a video demonstrating that this is the case - https://www.youtube.com/watch?v=zSW9J814b-w&feature=youtu.be

[video=youtube;zSW9J814b-w]https://www.youtube.com/watch?v=zSW9J814b-w&feature=youtu.be[/video]

My understanding is that a metal detector is simply detecting a change in its magnetic field's flux. Anything that can disturb that field can be detected subject to a number of variables (i.e. amount of material present, how conductive it is, how close it is to the detector, the detector's sensitivity, etc.).

I'm not sure how one would "shield" something from a metal detector, since the "shield" itself would disturb the magnetic field, right? Maybe someone smarter than me knows.

 

[JettaKnight]

You thought all those guys on the beach with metal detectors were going after what? Car keys? The car?

https://www.explainthatstuff.com/metaldetectors.html

Cue at 1:24.

[video=youtube_share;E7iSILfWm2Y]https://youtu.be/E7iSILfWm2Y?t=1m18s[/video]

 

[OurDee]

Metal detectors have come a long way. Mine can tell a lot about what is in the ground, how deep it is, and pin point it.