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Unformatted text preview: 1 March 5, 2008 Physics 132-Winter 2008 Prof. Jim Beatty-Ohio State 1 Physics 132 Introductory Physics: Electricity and Magnetism Winter Quarter 2008 Lecture 25 March 5, 2008 Physics 132-Winter 2008 Prof. Jim Beatty-Ohio State 2 Inductors Capacitance : how much charge we store for a given potential difference (self) Inductance: how much magnetic flux we store for a given current. C = q V L = N i Solenoid with current i: = BA N = nL B = o in L = N i = ( n )( BA ) i = ( n )( o in ) A i = o n 2 A Units of L: Henry [ Henry ] = [ Tesla m 2 ] [ Ampere ] 2 March 5, 2008 Physics 132-Winter 2008 Prof. Jim Beatty-Ohio State 3 Changing the Current in an Inductor i B Change i for an inductor. Faradays Law: EMF = N d dt = d ( Li ) dt Self-inductance: EMF = L di dt L = N i An inductor generates an EMF due to changes in its own magnetic field. In a circuit loop equation, an inductor gives a voltage change of -L di/dt in the direction of the current. For constant current, an inductor is like a wire. A sudden change in current produces large EMFs....
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