nagle_phys2020_fa07_lecture30

# nagle_phys2020_fa07_lecture30 - Clicker Question A...

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1 58 A conducting loop is halfway into a magnetic field. Suppose the magnetic field begins to decrease rapidly in strength. What happens to the loop? A. The loop is pushed upward, toward the top of the page. B. The loop is pushed downward, toward the bottom of the page. C.The loop is pulled to the left, into the magnetic field. D.The loop is pushed to the right, out of the magnetic field. E. The tension is the wires increases but the loop does not move. Clicker Question http://www.co.boulder.co.us/clerk/elections/ V ot e ! 59 Eddy Currents L x=vt v X X X X X X B The current induced in the moving bar is an example of an Eddy Current. 60 If a metal object (something in which electric charges can move) and an external source of Magnetic Field are in relative motion so that there is changing Magnetic Flux through the metal, then Faraday says there is an EMF and thus an Eddy current. If the metal is moving, then the direction of the current is always such as to cause a force which opposes the motion (slows the metal). Note that if the Eddy current force aided the motion, then you would get runaway motion (i.e. free energy), which is impossible. 61

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## This note was uploaded on 02/27/2008 for the course PHYS 2020 taught by Professor Dubson during the Fall '06 term at Colorado.

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nagle_phys2020_fa07_lecture30 - Clicker Question A...

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