Question

how dangerous are magnetic fields ?

Answer 1

I don't know much about it, but i found these

http://www.magnetotherapy.eu/magnetotherapy-magnetotherapy/magnetotherapy-harmful-strong-magnetic-field.php

http://www.ifp.illinois.edu/~hasegawa/emma/node2.html

Answer 2

they are always around us. in the environment they are harmless but if u go 140 T + it MAY affect u. but that only got generated once when they joined so many capacitors together to produce this pulse current that produced this huge magnetic field and it wasnt tested on human so no1 is really sure about it

Answer 3

i have recently got bought some small spherical neodymium magnets , how can i tell the frequency ?

Answer 4

or the magnetic field strength?

Answer 5

well, felix it depends , how destructive can you make it :)

Answer 6

Frequency? I didn't think magnets had frequencies. As for determining their strength, I suppose if you had a very sensitive ammeter you could connect it to a wire without anything in it and make a loop and then move the magnets in and out of the loop since a changing magnetic field induces a current. Once you measure the current you can use that to measure your magnetic field.

Answer 7

i didn't think magnets had frequencies either , but the second link seams to be going on about them,

i do have an ammeter ,
what are the relevant equations for determining Tesla from amps ?

Answer 8

The frequency you're referring to in the second article is the frequency of the AC electricity, it's the frequency of how fast the magnetic field is changing, because the electric current is constantly changing direction. It sounds like higher frequencies are more dangerous because they create rapidly changing magnetic fields, which in turn induce currents within the cells of the human body. Static magnetic fields can't induce a current.

A magnet like a neodymium magnet has a static magnetic field, it will only change if you move relative to the magnet... so avoid moving the magnet back and forth towards you over 100,000 times a second, and you should be fine :D

Answer 9

Static fields of small magnets are probably nothing to worry about health-wise.

http://hobbieroth.blogspot.com/2009/10/are-static-magnetic-fields-dangerous.html

@kainui @UnkleRhaukus the induced current will be proportional to how fast the magnetic field changes, ie how fast you can move the magnet, this likely won't allow you to learn much about a static field's strength. If you hold the magnet still, no current is induced. The faster you move it, the higher the current.

Answer 10

I found something you might like to try! http://m.everythingscience.co.za/grade-11/18-electromagnetism/18-electromagnetism-03.cnxmlplus



They give you this equation. E is the voltage, N is the number of turns of wire, B is the magnetic field strength, A is the area of circular wire loop, theta is the angle at which you move the magnet towards the loop, and t is the time you do it in.

\[E=-N \frac{ \Delta(BAcos \theta) }{ \Delta t }\]
With a little bit of magic I think we can combine this with ohm's law and also look online and measure the resistance by knowing the wire's material, length and diameter. http://www.cirris.com/testing/resistance/wire.html

\[\frac{ -IRt }{ NA }=B\] so by measuring I, the current and knowing the resistance R you might be able to measure it by timing yourself doing this. Although probably not since I have no idea what you'd be timing.

I hope someone comes up with a way for him to measure his magnetic field strength lol.