Word: electromagnets
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...Tests. If the object in Jimmy's eye had been of iron or steel, Colonel Passmore could have removed it with relative ease on his first try with an electromagnet. When he found that it was another material - almost certainly brass-all he could do was let the eye heal a little and hope to get at the object later. But there was grave danger that eye fluids would react with the metal and compel removal of the eye. Then Dr. Passmore remembered reading that Dr. Nathaniel Bronson II had begun work in New York on an ultrasound probe...
Using new techniques and novel materials, scientists have learned to construct permanent magnets of astonishing power. Into a small hunk of fancy alloy, or a little bit of fragile ceramic, they have built all the pulling power of a hefty electromagnet without its awkward current-carrying coils. But in spite of their handiness. the new magnets have a built-in flaw: their pull is permanent. They lack practical versatility because their fierce attraction for iron-bearing metal cannot be turned off at will, unlike the clumsiest electromagnet, which can be controlled by the flick of a switch...
...current is sent through the coil for a fraction of a second, most of the pulling power switches in an instant from one end of the magnet to the other. A few flashlight batteries can supply enough juice-not nearly so much as would be needed by an equivalent electromagnet...
...strongest magnetic field that Bell Labs can generate, 88,000 gauss (the unit of magnetism). It can carry more than 1,000 times as much current as a copper wire of the same size at normal temperature. Bellmen believe that it can be coiled into a superpowerful electromagnet with a field of at least 100,000 gauss...
...leave from his job as a Harvard physics professor, says of his work: "The thing that's so wonderful is that you get paid for telling the truth, just laying it out for anyone to do with as they will." It was a spare-time experiment with a borrowed electromagnet and a quarter's worth of paraffin that led to his Nobel-prizewinning "nuclear resonance" system for measuring atomic properties. In his early studies of the 21-cm. radio waves coming from hydrogen clouds in interstellar space, Purcell made do with a hastily devised antenna hung outside his Harvard laboratory...