# Tutorial 5 - voltage immediately after the switch is thrown...

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F i n a l M a r k : ECTE 290 Tut 5 Student Name: All questions 1 mark unless indicated. Total 10 Marks. 1. The time constant for a resistor and a capacitor in series connection is RC 2. The time constant for a resistor and an inductor in series connection is L/R 3. For a capacitor its voltage cannot change instantly. 4. For an inductor its current cannot change instantly. 5. (6 marks) 6. Known quantities: Circuit shown in Figure P5.22, . 23 , 7 , 17 , 11 , 130 , 35 3 2 1 2 1 = = = = = = k R k R k R F C V V V V S S µ Find: At t = 0 + the initial current through R 3 just after the switch is changed. Assumptions: None. Analysis: To solve this problem, find the steady state voltage across the capacitor before the switch is thrown. Since the voltage across a capacitor cannot change instantaneously, this voltage will also be the capacitor
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Unformatted text preview: voltage immediately after the switch is thrown. At that instant, the capacitor may be viewed as a DC voltage source. At t = − : Determine the voltage across the capacitor. At steady state, the capacitor is modeled as an open circuit: ( ) ( ) 2 1 = = − − R R i i Apply KVL: ( ) ( ) V V V V V V V S S C S C S 95 2 1 2 1 − = − = = − + − + − − At t = + : ( ) ( ) ( ) ( ) + + − + = − = = 95 3 2 R R C C i i V V V Apply KVL: ( ) ( ) ( ) ( ) ( ) mA R R V V i R i V R i V C S R R C R S 167 . 1 10 23 10 7 95 130 3 3 3 2 2 3 3 3 2 3 2 = × + × − = + + = = − + − + + + + +...
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## This note was uploaded on 10/27/2009 for the course ECTE 290 taught by Professor Zhengli during the Three '09 term at University of Wollongong, Australia.

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