Lec17-2VV - Lecture 17-1 Lecture It would appear that...

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Lecture 17 Lecture 17 -1 It would appear that earlier semesters also ran out of time in the previous lecture. Today is the opportunity to spend a proper amount of time on Induction and Faraday’s Law.
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Lecture 17 Lecture 17 -2 BRIDGE OF NAILS
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Lecture 17 Lecture 17 -3 Magnetic Flux $ 2 cos B BA B nA θ Φ= = ur ± $ B S B ndA ± B i B 1 Wb = 1 T m 2 $ 0 S BndA = ± ± Gauss’s Law for Magnetism over closed surface cos B NBA Φ = ( N turns)
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Lecture 17 Lecture 17 -4 MAGNETIC BRAKING 6D08
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Lecture 17 Lecture 17 -5 Faraday’s Law of Induction The magnitude of the induced EMF in conducting loop is equal to the rate at which the magnetic flux through the surface spanned by the loop changes with time. where $ B S B ndA Φ= ur ± Minus sign indicates the sense of EMF: Lenz’s Law Decide on which way n goes Fixes sign of ϕ B RHR determines the positive direction for EMF N N r E nc g d v s =− d Φ B dt . Enc ds ±
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Lecture 17 Lecture 17 -6 Induced Electric Field from Faraday’s Law / ε Wq = EMF is work done per unit charge: nc E d s = r r ± ± If work is done on charge q , electric field E must be present: nc ε Ed s = r r ± ± This form relates E and B! The induced E by magnetic flux changes is non-conservative. B ur ± • Note that for E fields generated by charges at rest (electrostatics) since this would correspond to the potential difference between a point and itself. => Static E is conservative . 0 s = r r ± Rewrite Faraday’s Law in terms of induced electric field : r E nc g d v s =− d Φ B dt .
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This note was uploaded on 04/23/2011 for the course PHYS 241 taught by Professor Wei during the Spring '08 term at Purdue University-West Lafayette.

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Lec17-2VV - Lecture 17-1 Lecture It would appear that...

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