25_Chapter 20 HomeworkCH20 Induced Voltages and Inductance

25_Chapter 20 HomeworkCH20 Induced Voltages and Inductance...

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Induced Voltages and Inductance 199 20.65 Consider the closed conducting path made up by the horizontal wire, the vertical rails and the path containing the resistance R at the bottom of the figure. As the wire slides down the rails, the outward directed flux through the area enclosed by this path is decreasing as the area decreases. This decreasing flux produces an induced current which flows counterclockwise around the conducting path (and hence, right to left through the horizontal wire) to oppose the decrease in flux. The wire is now carrying a current toward the left through a magnetic field directed out of the page. The field then exerts an upward magnetic force on the wire of magnitude ( ) ( ) () = 2 22 sin90 B Bt BB A t Bv FB I B RR R R ∆Φ ∆∆  = = ==   l l ll E l ) t vv = R Observe that this upward directed magnetic force opposes the weight of the wire, and
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This document was uploaded on 10/20/2011.

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