# tsl248 - • Motion of bar magnet causes d Φ B dt > ....

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Faraday’s Law of Induction (1) Prototype: motional EMF reformulated. Choose area vector ~ A for current loop: A = Ls J . Magnetic flux: Φ B = R ~ B · d ~ A . Here Φ B = - BLs . Motional EMF: E = vBL . Change in area of loop: dA = Lds . Change in magnetic flux: d Φ B = - BdA = - BLds . SI unit of magnetic flux: 1Wb=1Tm 2 (Weber). Rate of change of flux: d Φ B dt = - BL ds dt = - vBL. Faraday’s law: E = - d Φ B dt . I L v s ds Α B tsl248 – p.1/2

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Faraday’s Law of Induction (2) Here the change in magnetic flux Φ B is caused by a moving bar magnet. Assume area vector ~ A of loop pointing right. Hence positive direction around loop is clockwise.
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Unformatted text preview: • Motion of bar magnet causes d Φ B dt > . • Faraday’s law: E =-d Φ B dt . • Induced EMF is in negative direction, E < , which is counterclockwise. • Induced EMF reflects induced electric field: E = I C ~ E · d ~ ‘. • Field lines of induced electric field are closed. • Faraday’s law is a dynamics relation between electric and magnetic fields: I C ~ E · d ~ ‘ =-d dt Z S ~ B · d ~ A. tsl249 – p.2/2...
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## This note was uploaded on 04/30/2008 for the course PHYS 204 taught by Professor Andrevantonder during the Spring '07 term at Rhode Island.

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tsl248 - • Motion of bar magnet causes d Φ B dt > ....

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