SF.

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	733 reputation	bio	website		visits	member for	2 years, 2 months
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2d	comment	Does the slip-stick phenomenon have any application? While this isn't the naturally occurring slip-stick effect, the ABS system in car brakes emulates/induces something very similar to reduce braking distance.
May 15	comment	Rough, easy DIY method of measuring magnetic field strength That's nifty, although probably beter suited for weaker fields. Still - to know the absolute value of the field from the ratio I should know the local strength of earth's magnetic field. How would I go about finding it?
May 14	awarded	Popular Question
Apr 18	answered	Would a phone move upon vibration in a completely uniform situation?
Apr 2	comment	Argument against computer consciousness may I suggest philosophy.stackexchange.com ?
Mar 29	awarded	Benefactor
Mar 29	accepted	How do permanent magnets manage to focus field on one side?
Mar 28	comment	How do permanent magnets manage to focus field on one side? It appears this is the right track at least - the mysterious metal the magnet is glued to acts as a shield - I didn't know shielding magnetic field like this was possible at all...
Mar 28	comment	How do permanent magnets manage to focus field on one side? If I hold the U-shaped magnets tip-to-tip with tips as far as they are when you put the two butt-to-butt they won't visibly attract each other either. The force is normally inversely proportional to distance from the pole but here 3mm from the pole it's near zero.
Mar 28	comment	How do permanent magnets manage to focus field on one side? @AlecS: Except in U-shaped magnet the field is sitll strong some 3cm away from the pole in direction opposite than the other pole - something like reverse square of distance from the pole is observed in all directions - the arced part not showing much attraction because it's very far from the poles. Here, 3mm from the pole in one direction the field's strength can almost cause injury, 3mm from the pole in opposite direction it's near zero.
Mar 27	revised	How do permanent magnets manage to focus field on one side? photos
Mar 27	comment	How do permanent magnets manage to focus field on one side? I wonder too - but it doesn't look like the case here. I tried to stick a normal magnet to it - one side - it has two poles, located on the "active surface" symetrically off-center.
Mar 27	comment	How do permanent magnets manage to focus field on one side? @Alex: When I stick them the "working sides" together it appears there are some zones of attraction and repulsion - I can't rotate them freely nor slide against each other. But the backsides seem completely inert, no attraction/repulsion, reacting like plain ferromagnetic metal to other magnets or if sticking the two neutral-to-active side.
Mar 27	comment	How do permanent magnets manage to focus field on one side? @ColinFredericks: It seems there's some 2mm thick magnet glued on surface of some 3mm ferromagnetic sheet metal larger than the magnet itself. The metal appears to work like a shield, reacts to normal magnets like normal ferromagnetic metal (as if the neodymium magnet wasn't there at all). If there is any repulsive force, it feels to completely cancel out with attraction - both magnets seem not to affect the metal pieces at all - normally sticking a magnet to a ferromagnetic will make it act like a magnet as long as the contact is held, not in this case, the alloy "doesn't see" the neodymium.
Mar 27	awarded	Promoter
Mar 25	comment	Is it possible to get energy from electrical wire using induction? Actually, this "wireless energy transfer" is in common use nowadays - lots of electric toothbrushes, shavers etc use that for charging their batteries - leaving no contacts exposed, charging through plastic case. The idea is "a transformer with its magnetic core cut in two pieces, one with primary, the other with secondary coil." A small gap between the two halves of the core generates some loss but removes need for electric contact (or even touch) between the two coils.
Mar 24	awarded	Yearling
Mar 24	answered	Why does higher acceleration minimize a car's fuel consumption?
Mar 24	comment	How do permanent magnets manage to focus field on one side? @Tziolkovski: While I concede U-shaped magnet might be another example of such a magnet as the ones I asked about, your answer still doesn't explain why they act that way - you just added a third example to my two.
Mar 24	comment	How do permanent magnets manage to focus field on one side? @Tziolkovski: I edited my question thoroughly to remove the confusion of future answerers that I meant something else than I asked. (the upvotes your answer gained would suggest that people really thought I meant unipolar. I never did. And no, 100% one-sided is not possible. You can reduce the the field density by many orders of magnitude but you can't completely remove it.) U-shaped and disk head are the obvious examples of focusing the field in one place. Not nearly zeroing it without affecting shape of the magnet - your answer didn't answer my question, thus downvote.