6 ms·
On the subject of interesting magnetic effects, a lot of people don't know that pretty much all matter is magnetic, just that the strength of the interaction is
by dkhar 12y ago
On the subject of interesting magnetic effects, a lot of people don't know that pretty much all matter is magnetic, just that the strength of the interaction is a lot smaller than what we're used to with ferromagnets.
All materials exhibit a diamagnetic (pushes against the field) effect, but in many materials, that effect is overwhelmed by a competing paramagnetic (pushes in the direction of the field) effect. Most of the things we call "magnets" exhibit ferromagnetism, which typically produces much stronger forces than either of the previous two.
H2O is particularly interesting, because it's actually diamagnetic, and will push away from magnetic fields. Given a strong enough magnet, you can have a lot of fun with this effect by putting common water-filled objects in its field:
http://www.ru.nl/hfml/research/levitation/diamagnetic/ http://www.ru.nl/hfml/research/levitation/diamagnetic/
- snarfy 12y agoAnother fun fact: Magnetic fields are a consequence of relativity and length contraction of electric fields. http://physics.weber.edu/schroeder/mrr/MRRtalk.html http://physics.weber.edu/schroeder/mrr/MRRtalk.html This video also talks about it: https://www.youtube.com/watch?v=1TKSfAkWWN0 https://www.youtube.com/watch?v=1TKSfAkWWN0
- hrjet 12y agoNitpick: relativity can explain magnetism, not cause magnetism.
- snarfy 12y agoTrue, it explains them in terms of electric fields, but we still don't know what those are.
- readerrrr 12y agoWe know: http://en.wikipedia.org/wiki/Electric_field http://en.wikipedia.org/wiki/Electric_field http://en.wikipedia.org/wiki/Electric_charge http://en.wikipedia.org/wiki/Electric_charge http://en.wikipedia.org/wiki/Quantum_electrodynamics http://en.wikipedia.org/wiki/Quantum_electrodynamics An electric field is generated by electric charge and time-varying magnetic fields Charge is the fundamental property of forms of matter that exhibit electrostatic attraction or repulsion in the presence of other matter. Electric charge is a characteristic property of many subatomic particles.
- danbruc 12y agoNitpicking again - the fields are a working mathematical description but, as far as I know, we don't know if or in what sense they are real things, whatever real thing even means. The electrical and magnetic fields change when you switch reference frames, so that does not sound like something that really exists independent of an observer. The vector potential on the other hand does not change but it does not seem real either because it has gauge symmetry.
- snarfy 12y agoWe know that the A field is more fundamental (at least Feynman thought so): http://en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect http://en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect
- deleted 12y ago[deleted]
- mrfusion 12y agoInteresting. Does it explain permanent magnets too?
- agumonkey 12y agoSo a MF is just a twisted EF diffusion ? /me on his way to watch that video