Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: neilep on 06/02/2006 04:34:52

Title: Magnetic Capability
Post by: neilep on 06/02/2006 04:34:52

Is there a limit to the strength of magnetic force that can be processed/developed ?

Say you had an endless supply of power, assuming no unreliability and practical issues, could you in theory make a magnet so strong that it could interfere with the planets magnetic field ?

Is size of magnet relative to it's magnetic strength ?


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Title: Re: Magnetic Capability
Post by: Soul Surfer on 06/02/2006 15:01:20

There are technological limits to magnetic field generation but no real physical ones.  Magnetars ( a form of rapidly rotating neutron star with an enormous magnetic field) can produce fields many orders of magnitude greater than any that can be produced on earth.

Permanent magnets have clear limits relating to the residual field in ferromagnetioc materials and the physical volume of material that they can contain.

superconducting magnets have similar limitations.

For higher fields you need to use electromagnets but the creation of a magnetic field using electrical currents flowing in coils causes physical stresses in the materials like to those produced on magnetic material being attracted by the magnet and thermal stresses caused by the heating of the conductive material by the current flowing.  This means that continuous magnetic fields are limited by the ability to cool the magnet coil and prevent it from melting  while pulsed magnets are limited by the physical strengths of the materials being used.

It would be relatively easy to interfere with the earth's magnetic field provided you made a big enough electromagnet.  If you wound a single turn around the equator.  The current required would not be all that great  (less than 1 amp if I remember rightly).  However as the field of electromagnets falls off as the cube of distance. You would always need to build an electromagnet that was significant in size with respect to the earth if you wanted to do it.

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Title: Re: Magnetic Capability
Post by: neilep on 06/02/2006 17:02:13

Ian...Thank you very much indeed for your clear and concise answer. It's appreciated.

So size is definitely relative to magnetism. Perhaps in the future we may develop materials that will miniaturize the dimensions. Though it sounds incredible to wrap a single turn around the equator, it's certainly feasible, and perhaps may be necessary in the future to take such extreme action.

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