TheKids have been learning a bit about Magnet Ism.

There are a few categories of interesting examples

• the [Planet Earth]

  • approximate magnetic [DiPole]

  • explained by [Dynamo Theory], based on sloshing around of liquid iron in planet's outer core, but sounds suspiciously like a [Perpetual Motion] machine

  • more than 10deg off from geographic poles, and not exactly opposite each other

  • the [Magnetic Pole]-s are moving, some say accelerating

  • the poles occasionally reverse (north/south). Some have theorized that the recent acceleration in movement of the poles is a warning sign that a reversal will happen "soon". The effects of such a reversal are debated. Even if it doesn't trigger some crazy Climate Change, it could be mess with communication and computer systems (though probably less immediately/locally significantly than an EMP bomb, though obviously its effects would be global and longer-lasting).

• [Permanent Magnet]-s

  • The spin of an electron, combined with its orbital angular momentum, results in a magnetic dipole moment and creates a magnetic field. (The classical analogue of quantum-mechanical spin is a spinning ball of charge, but the quantum version has distinct differences, such as the fact that it has discrete up/down states that are not described by a vector; similarly for "orbital" motion, whose classical analogue is a current loop.) In many materials (specifically, those with a filled electron shell), however, the total dipole moment of all the electrons is zero (e.g., the spins are in up/down pairs). Only atoms with partially filled shells (e.g., unpaired spins) can experience a net magnetic moment in the absence of an external field. A ferromagnetic material has many such electrons, and if they are aligned they create a measurable macroscopic field. I hope you understood that.

  • Thus, an ordinary piece of iron generally has little or no net magnetic moment. However, if it is placed in a strong enough external magnetic field, the domains will re-orient in parallel with that field, and will remain re-oriented when the field is turned off, thus creating a "permanent" magnet. This magnetization as a function of the external field is described by a hysteresis curve. Although this state of aligned domains is not a minimal-energy configuration, it is extremely stable and has been observed to persist for millions of years in seafloor [Magnet Ite] aligned by the Earth's magnetic field (whose poles can thereby be seen to flip at long intervals).

• [Electro Magnet]-s

  • loop a wire over and over, run a current through it

Stimulating Learning Projects? well, you can play with iron filings, and make an [Electro Magnet], but since nobody really can understand how they work, it seems more like a magic trick to me...

Jesus, why do they try Educating Kids about this stuff?

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