lecture18 - Physics 2102 Faradays law Physics 2102 Gabriela...

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Unformatted text preview: Physics 2102 Faradays law Physics 2102 Gabriela Gonzlez Solenoids, dipoles B = m in B ( z ) m 2 p r m z 3 = An electrical current produces a magnetic field. dA Faradays Law A magnetic field can create a en electrical current too! If we define magnetic flux, similar to definition of electric flux, but for an open surface with an edge: B n dt d EMF B - = = S B dA n B Take note of the MINUS sign!! The induced EMF acts in such a way that it OPPOSES the change in magnetic flux (Lenzs Law). Then a time varying magnetic FLUX creates an induced EMF, and thus an electrical current if the edge is a wire!: Example When the N pole approaches the loop, the flux into the loop (downwards) increases The loop can oppose this change if a current were to flow clockwise, hence creating a magnetic flux upwards. So, the induced EMF is in a direction that makes a current flow clockwise. If the N pole moves AWAY, the flux downwards DECREASES, so the loop has a counter clockwise current! Example A closed loop of wire encloses an area of 1 m2 in which in a uniform magnetic field exists at 300 to the PLANE of the loop. 300 to the PLANE of the loop....
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This note was uploaded on 11/18/2011 for the course PHYSICS 2102 taught by Professor Dowling during the Fall '10 term at LSU.

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lecture18 - Physics 2102 Faradays law Physics 2102 Gabriela...

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