# Giant Magnet Question

#### Bendevlin

Aug 18, 2023
1
Hi There

Need some advice. Am writing a novel about someone who’s trying to erase some audio tapes that are inside an old Victorian steel safe. His plan is to wrap the safe in copper wire and create a magnetic field with a car battery.

He’s 22 and a bit naive. Might it work? Would there be sparks and smoke - or other consequences?

does anyone have any theories or experiences?

Thoughts appreciated

thanks, Ben

#### Bluejets

Oct 5, 2014
6,713
The steel casing becomes a shield.
First thoughts...OMG, another Macgiver.....world canot handle two...
In simple terms, no work.......

#### Martaine2005

May 12, 2015
4,785
It’s a novel, anything can happen!.

Martin

#### kellys_eye

Jun 25, 2010
6,231
Technically it won't work as the steel will contain the magnetic field and prevent it from 'entering' the tape - much like a Faraday cage will protect electronics from an EMP.

Equally he wouldn't get sufficient magnetic field density using a car battery. Plenty of current, not enough voltage given the size of the coil required.

But you need only watch anything from Hollywood to understand that 'physics' usually doesn't come into it when telling a story!

Write it as if he 'thinks' he's doing it correctly but use plot twist where, once the safe is eventually opened, the person accessing the tape carries it through a rigged-with-a-coil doorway (or over a mat) or even a coil secreted (unbeknown to the person) on his/her own person etc....

#### Delta Prime

Jul 29, 2020
1,642
Trick question and static magnetic field will penetrate your safe (Faraday cage)! Ever try taking a compass into a Faraday cage? Compass still works. I did that when I was 10 years old on field trip grade school science class.
A repulsive Force occurs because of the conservation of energy.
Lens law Eddy currents occur on the conductive surface of your safe because of the "work done" sets the Eddy currents in motion imparting kinetic energy to the electrons forming the Eddy currents. A repulsive Force is felt in lens law,so that work is done by
pushing the magnetic field into the conductive medium. Just place the world biggest magnet in front of the safe.You're magnetic audio tapes inside the Victorian safe will be wiped clean.

#### Bluejets

Oct 5, 2014
6,713
Trick question and static magnetic field will penetrate your safe (Faraday cage)! Ever try taking a compass into a Faraday cage? Compass still works. I did that when I was 10 years old on field trip grade school science class.
A repulsive Force occurs because of the conservation of energy.
Lens law Eddy currents occur on the conductive surface of your safe because of the "work done" sets the Eddy currents in motion imparting kinetic energy to the electrons forming the Eddy currents. A repulsive Force is felt in lens law,so that work is done by
pushing the magnetic field into the conductive medium. Just place the world biggest magnet in front of the safe.You're magnetic audio tapes inside the Victorian safe will be wiped clean
What a load of crap..........MacGiver is alive ...Again!!

#### Delta Prime

Jul 29, 2020
1,642
What a load of crap..........MacGiver is alive ...Again!!

Last edited:

T
Replies
10
Views
1K
Terry Given
T
Replies
9
Views
1K
P
Replies
2
Views
1K
terryc
T
H
Replies
1
Views
2K
W
Replies
19
Views
2K
David Harmon
D