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Unformatted text preview: 10/4/11 1 Chapter 20 *RIGHT HAND RULES 10/4/11 2 Chapter 20 *RIGHT HAND RULES 10/4/11 3 Chapter 20 *RIGHT HAND RULES L !" L !" 3 L !" 3. is taken in the direction of I. L !" wire with a current in a Feld: B !" 10/4/11 4 Chapter 20 *RIGHT HAND RULES Right-hand rule number 4 * Direction of B : Use the right hand rule. Curl fingers in direction of current flow in loop and thumb points in the direction of B. 10/4/11 5 RL Circuits Initially, an inductor acts to oppose changes in current through it. A long time later, it acts like an ordinary connecting wire. 10/4/11 6 RL Circuits ( ! on) I = ! R 1 " e " Rt / L ( ) = ! R 1 " e " t / # RL ( ) V L = ! e " Rt / L = ! e " t / # RL Current Max = ! / R 63% Max at t = L / R Voltage on L Max = ! / R 37% Max at t = L / R 10/4/11 7 RL Circuits R I ! a b L I Why does " RL increase for larger L? Why does " RL decrease for larger R? L opposes change in current & slows down the rate of change Large R decreases final current easier charge up goal Large R dissipates energy quicker, speeds up discharge of inductor (speeds up current loss) 10/4/11 8 Sources 10/4/11 5 RL Circuits Initially, an inductor acts to oppose changes in current through it. A long time later, it acts like an ordinary connecting wire....
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- Fall '08