Science News

Electromagnetic force strengthening

Sun, 4th Mar 2012

Dave Ansell

Part of the show Can we Trust the Upper Classes?

There are many areas of modern life that are driven by electromagnetic forces, from electric motors, and Magnetised Irondoor locks to experimental long range artillery.

It would also be very useful to be able to make objects levitate for transport or just low friction bearings, without using superconductors, this involves using rapidly changing magnetic fields which induce currents in other objects. To produce a very large force, you need very strong fields, and whilst magnetic fields aren’t very bad for humans, electric fields can cause problems.

Ways of strengthening these forces would be immensely useful, in fact we already use materials which concentrate magnetic fields - ferromagnets like iron which are attracted to magnets and are said to have a positive permeability. But there is a limit to the effect they can produce, and iron is heavy.

Yaroslav Urzhumov and collegues may have invented a way of helping, they suggest using a material which can have a negative permeability - it is repelled rather than attracted to magnets. These materials would have to be a metamaterial designed carefully and consisting of a large number of tiny coils which have currents sloshing back and forth inside them, these can be made to resonate by the changing magnetic field. By making a composite of these materials and conventional positive permeability materials it is possible to hugely increase the forces involved. Possibly increasing them by a factor of 10,

They haven't been built yet but this could make many devices smaller and particularly lighter as the metamaterials are mostly plastic and air rather than metal, and make machines more efficient plus make new applications practial.



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Very interesting but they would have to be excited at a relatively narrow range of frequencies Soul Surfer, Thu, 8th Mar 2012

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