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Homework Help: Circuit/Current/Resistance Problem

  1. Jul 24, 2009 #1
    I need help finding the current in a series circuit with 3 resistors! I have Vs = 12V, R1 = 220ohms, at R2 has a voltage drop = 7V, and at R3 has a voltage drop = 2.5V. How do I find the current? I Know I have to add up all the resistors but how do I find the other 2 unknown resistors?
  2. jcsd
  3. Jul 24, 2009 #2


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    Staff: Mentor

    Welcome to the PF.

    Think of those two resistive voltage drops just as voltage sources for a moment. What is the net voltage that is across the 220 Ohm resistor then? Does that help you to find the series current that is flowing around the whole circuit?
  4. Jul 24, 2009 #3
    Holy!!! You are brilliant. I test it and it works! I will keep this in my note. Thank you Berkeman!!!
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