Infinite strength magnetic field?

[aurumdeus]

I first asked this question to my physics teacher, but she was unable to answer me. I was wondering if anyone here could help.

The strength of a magnetic field (as with anything else which spreads out evenly in 3 dimentions) operates on an inverse square proportion. As you halve the distance to the origin of the magnetic field, you quadruple the strength of the field. But as you can only take a fraction of the total distance, you can never reach the origin and the strength of the field continues to increase. Surely this would result in a magnetic field of infinite strength, the closer you go? Or if it does not then why is this so?

[BEAKER]

I would think it has to do with the total maximum strength of the original magnet(s) which you could not go beyond.

[infamous]

Originally Posted by aurumdeus

I first asked this question to my physics teacher, but she was unable to answer me. I was wondering if anyone here could help.

The strength of a magnetic field (as with anything else which spreads out evenly in 3 dimentions) operates on an inverse square proportion. As you halve the distance to the origin of the magnetic field, you quadruple the strength of the field. But as you can only take a fraction of the total distance, you can never reach the origin and the strength of the field continues to increase. Surely this would result in a magnetic field of infinite strength, the closer you go? Or if it does not then why is this so?

Ask yourself this question aurumdeus: If the initial strength of the magnet were infinite, what is a fraction of infinity? I believe you will agree that one half of infinity is still infinity. Therefore, the initial strength of any magnet cannot be infinite.

[Turtle]

___Wouldn't the smallest possible magnet be a single atom, or if not a single atom then say a molecule of the mineral magnetite? Just search this site for "infinity" & you'll find no end of discussion. In this case, I'd say it's a red herring.

[Kirk Gregory Czuhai]

the magnetic field is caused by the spin states being aligned by the outer electrons in a permanent magnetic or uniform direction flow of a electo-magnetic. another magnetic material can only approach the first so close and no further because of the Pauli-exclusion principle as electrons are Fermions and have anti-symetric wave functions.

[Turtle]

___I believe How many atoms, that is what is the fewest atoms, required to make a permanent magnet? Whichever kind of atoms, ie. element is best I realize may affect the answer.

[BEAKER]

Originally Posted by Kirk Gregory Czuhai

the magnetic field is caused by the spin states being aligned by the outer electrons in a permanent magnetic or uniform direction flow of a electo-magnetic. another magnetic material can only approach the first so close and no further because of the Pauli-exclusion principle as electrons are Fermions and have anti-symetric wave functions.

WOW!

[Qfwfq]

The smallest magnet is a lepton, for example an electron. A magnet, however, is a dipole and not a monopole, so the field doesn't go by the inverse square law as it would for a monopole.

Let's consider the question for the electric field:

If the charge is point-like, as it is for the electron as far as wee can currently detect, then the limit for r --> 0 is indeed infinity. From the classical pov at least.

Originally Posted by infamous

If the initial strength of the magnet were infinite, what is a fraction of infinity? I believe you will agree that one half of infinity is still infinity. Therefore, the initial strength of any magnet cannot be infinite.

Not a conclusive argument at all, I'd fail you if you wrote that on a calculus test!

Of course inf/a = inf, but from that it doesn't follow that the limit can't be inf.

[aurumdeus]

Originally Posted by infamous

If the initial strength of the magnet were infinite, what is a fraction of infinity? I believe you will agree that one half of infinity is still infinity. Therefore, the initial strength of any magnet cannot be infinite.

I agree that it does not seem right that the magnetic field can have an infinite strength, but the more I think about it the more it seems that it does.
However, in life, this seems obsurd. for example, a bar magnet is comprised of many magnetic particles. even if not infinite, then the strength at the distance from atom to atom must still be phenomenal. Why is it that the magnet does not simply burst apart? even with the strength of the bonds between the atoms, can they really be stronger than the magnetic field at this scale?

[bumab]

You never actually touch the magnets together, and since the ends operate under the inverse square law (i believe), it can still be really strong. the electrons will not touch each other, because of electromagnetic repulsion, and as they get closer, that repulsive force gets stronger.

only in collapsed stars can a force overcome the electon repulsion barrier, which is how neutron stars form (the electrons are finnally smashed together with the protons). There is a second barrier, which keeps neutrons from smashing together. If that's also broken by gravity, you get a black hole.

Am I correct in that summary? I can't recall the exact terms for it, but it seems to make sense.