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Unformatted text preview: song (shs546) Practice HW 15 Solutions weathers (22202) 1 This print-out should have 9 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 0.0 points A cubic magnet is levitating above a super- conducting surface. ? ? i N S Determine both the direction of the in- duced magnetic moment vector , and the direction of the induced current (as viewed from above). Let CW stand for clockwise, and CCW for counterclockwise. 1. vector is down, current is 0 2. vector = 0, current is CW 3. vector is up, current is CCW 4. vector = 0, current is CCW 5. vector is down, current is CW correct 6. vector is up, current is CW 7. vector is down, current is CCW 8. vector is up, current is 0 Explanation: Magnetic induction induces eddy-currents in a superconducting medium. In order to levitate the magnet, there must be a magnetic field created by the induced current. If we adopt the view of a current loop as a little bar magnet (magnetic moment vector ), its south pole must point up to repel the levitating magnet. Therefore, since vector in the same direction as the north pole of its repre- sentative bar magnet,, vector points down. To an observer above the setup, the induced current must run clockwise to create a magnetic field pointing downward....
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- Spring '00