chp29b - Q What is the direction of the induced current? A...

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MAGNETIC INDUCTION AND FARADAY’S LAW “It is possible that a magnetic field can produce an electric current.” Joseph Henry and Michael Faraday An induced emf is produced by a changing magnetic field. Electromagnetic Induction
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Current Induced by Magnet Moving Near Coil
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Magnetic Flux A B BACos A B B A d B B r r r r = = = Φ = Φ q ( Total Flux )
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Faraday’s Law of Induction nduced emf E is caused by the change in the magnetic flux. How about minus sign? Lenz ‘ s law A B B R i dt d B r r = Φ = Φ - = N loops I e e
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Lenz’s Law An induced emf is always in a direction that “opposes” the change in the flux flux increasing flux decreasing induced emf will create a current to reduce it. induced emf will create a current to increase it. .
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Three ways to change the magnetic flux. 1) By changing intensity of the magnetic field B 2) By changing area A of the loop. 3) By changing orientation of the loop with respect to the field (changing ).
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Unformatted text preview: Q What is the direction of the induced current? A square coil of wire with side 5.0 cm contains 100 loops and is perpendicular to a uniform 0.60 T magnetic field. It is quickly and uniformly pulled from the field to a region where B drops to zero. At t=0, the right edge of the coil is at the edge of the field. It takes 0.100 s to move the whole coil into the field free region. (a) Find the rate of change of the flux. (b) Find the emf and induced current. (c) How much energy is dissipated in the coil if its resistance is 100 ohms. (d) What was the average force required? EMF Induced by a moving conductor EMF Induced by a moving conductor The distance the rod travels: The area swept by the rod: Change in the flux: Magnitude of emf dx dt v dx vdt l dA Blvdt dA B d B Blv dt Blvdt dt d B ⋅ = ⋅ = = ⋅ = = = = f f e AC GENERATOR...
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This note was uploaded on 03/07/2011 for the course ECON 101 taught by Professor Carlos during the Fall '08 term at Oregon State.

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chp29b - Q What is the direction of the induced current? A...

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