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Homework Help: Current Problem

  1. Jul 23, 2007 #1
    1. The problem statement, all variables and given/known data

    The currents are flowing in the direction indicated by the arrows. A negative current denotes flow opposite to the direction of the arrow. Assume the batteries have zero internal resistance.

    http://img123.imageshack.us/img123/2045/599c898aa10950d7027807dyc7.th.jpg [Broken]

    A) Find the current through the 14.4Ω resistor and the 8.6 V battery at the top of the circuit. Answer in units of A.
    B) Find the current through the 23.2 Ω resistor in the center of the circuit. Answer in units of A.

    2. Relevant equations
    Kirchhoff's Junction and Loop Rules

    3. The attempt at a solution

    By applying the Kirchhoff's voltage law to the above loop I get
    8.6V - (23.2Ω)I1 - (14.4Ω)I = 0

    23.2I1 + 14.4I = 8.6 ..............................(1)

    Applying the Kirchhoff's voltage law to the down loop I get

    16.4V + (23.2Ω)I1 = 0

    I1 = - 0.71A

    Substitute this value in the eq(1)

    8.6V + (23.2)(0.71) = 14.4I

    I = 1.74A

    Therefore the current passes through the battery 8.6V and the resistance 14.4Ω is 1.74A

    For Part B, I thought that the current would be equal to I1 which I already solved for in Part A, so the current would be -0.71 A.

    I've pretty much worked everything out but I was hoping if someone could tell me if I was doing it right or not. I'm not too confident when it comes to these problems. Any comments would be very helpful. Thanks!
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Jul 23, 2007 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    Everything looks good, except for the picture, where all the currents are labeled by the same label (I). The answers are both correct.
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