Q3_7B_W10_Solution

Q3_7B_W10_Solution - voltage drop across R 2 30V = I 2 R 2...

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Name: , DL Section: Last First Office Use Quiz 3 Physics 7B Winter 2010 Jan. 27, 2010 1. Consider the circuit shown in the diagram above. a) The switch is initially open. What is the magnitude and direction of the current flowing through resistor 2? 30V 20V = I(300 ) + I(100 ) 10V = I(400 ) I = 10V/400 I = 25 mA b) The switch is closed, and a current of 129 mA is measured in the ammeter. How much power is dissipated in resistor 2? First we need to determine the current in resistor 2. To do that, let
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Unformatted text preview: voltage drop across R 2 . 30V = I 2 R 2 + I 3 R 3 30V = I 2 (300 )+(0.129A)(100 ) 30V-12.9V=17.1V= I 2 (300 ) I 2 =17.1V/300 =57mA Now determine the power: P=I 2 R=(57mA) 2 (300 )=0.974W c) Now consider R 3 to be shorted with a wire. How much power is now dissipated in R 2 ? I 2 =30V/300 =100mA P=I 2 R=(100mA) 2 (300 )=3.0W R V R E V / I IV P IR-2 2...
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