Is it related to atomic structure of a substance?
Basically a substance has to be magnetically active ( like iron) and its domain structure has to be all in the one direction.
According to a tour I recently took at an underground railroad house in Memphis, Tn, this is supposed to have accured. First I had heard of it, but instead of the brick, children were lined at the bottom of the bed in order to warm the occupants.
Yes, its very true. Southern plantation owners and enslavers used to use Black babies as foot warmers. They used Black babies as alligator bait too.
Flux lines in a magnetic field can be measured and used in many ways, but magnetism in general is a strange and mysterious force. Electromagnetic fields as used in electric motors and ferrous magnets (iron) from the size of a coin to the size of our Earth are electrons and probably other forces that we are just now discovering like string particals and other Quantum physics. I am an INDUSTRIAL ELECTRICIAN and we had to study motors and magnets and lagging and leading phases of alternating currents. It was very interesting. All these forces can do many, many wonderful things. Scientists and Electrical engineers are finding new ways to use these forces every day. I wish I could explain it better but my expertise is very limited. Me and sons play with powerful magnets and little motors and other gadgets as often as possible for fun and learning. As for atomic structure, it is absolutely related. I think it has to do with the valence electrons of each basic element but there is ALOT more to it than that. If you look at a chart of elements, notice that good conductors of electricity (silver, gold, copper) has 1 or 2 valence electrons. Insulators have 7 or 8. And semiconductors like silcone has 3 or 4. There are uncountable numbers of relationships between forces and matter!!
An electron revolving round the nucleus is a current loop and hence has a magnetic moment equal to the product of the current and area of the loop. If the resultant of all magnetic moments of all the electrons is zero then the material has no magnetism m in it. A magnetic material has a domain structure. In each domain al atoms are arranged with their magnetic moments parallel. That is each domain is like a magnet. If the net magnetic moment of all these domains is zero, then there is no magnetism in it. If this is placed in a strong external magnetic field, the domains arrange themselves under the influence of external field in a parallel direction, thus forming a strong magnet. The external energy is used to do the work necessary to turn all the domains. If all the domains return to their original position, when the external field is removed then there will be no magnetism in the material. In fact, only few domains change their position and hence there is a net magnetism present in the material. Thus it is a permanent magnet. There is a magnetic field around this magnet. The external work done is stored in the magnet. Unless the domains are altered ,it will not loose its magnetism.
