Lec19 - Lecture 19-1 RL Circuits Starting Current 1. Switch...

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Lecture 19-1 RL Circuits – Starting Current 0 dI IR L dt ε −− = 2. Loop Rule: 3. Solve this differential equation ( ) /( / ) 1 t LR Ie R = τ =L/R is the inductive time constant [ ] 22 // / / Tm A Tm A LR s VA ⋅⋅ = = 1. Switch to e at t=0 0 0 I = As the current tries to begin flowing , self-inductance induces back EMF , thus opposing the increase of I . + - ε/R /( / ) L dI VL e dt = =
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Lecture 19-2 Alternating Current (AC) = Electric current that changes direction periodically ac generator is a device which creates an ac emf/current. ac motor = ac generator run in “ reverse” A sinusoidally oscillating EMF is induced in a loop of wire that rotates in a uniform magnetic field. ( ) cos cos B NBA NBA t θ ωδ Φ= = ( ) ( ) sin B d NBA t dt ε ω Φ = = + 2 2 f T π ωπ = where
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Lecture 19-3 ©2008 by W.H. Freeman and Company
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Lecture 19-4 READING QUIZ 1 \ Which of the following statements is correct ? A| In A.C. circuit with a A.C. generator and an ideal capacitor the current lags the voltage. B| In an A.C. circuit with a A.C. generator and an ideal inductor the current leads the voltage. C| In an circuit consists of an ideal inductor and an ideal capacitor.
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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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Lec19 - Lecture 19-1 RL Circuits Starting Current 1. Switch...

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