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Resistors in parallel

  1. May 11, 2013 #1
    1. The problem statement, all variables and given/known data

    I have a circuit with two resistors in series that are in parallel to another resistor. Each resistor is 5Ω. The total current running through the series is 4amps. I need to find the current in the single resistor that is in parallel. What is the relationship among these three resistors in regard to current??

    2. Relevant equations

    for series Itotal=I1=I2=I3

    3. The attempt at a solution

    for parallel Itotal=I1+I2+I3
  2. jcsd
  3. May 11, 2013 #2


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    What is the voltage drop through each branch of resistors in parallel?
  4. May 11, 2013 #3
    I believe that something that could be useful here is the fact that voltage is the same across all elements that are parallel to one another in a circuit. I'm just not sure what you mean by the total current running through the series is 4 amps. Do you mean that the total current running through the resistor that is in series with the two resistors in parallel is 4 amps? It would be helpful to see a circuit diagram to answer this question.
  5. May 11, 2013 #4

    Andrew Mason

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    Apply Ohm's law to determine the voltage across the two series resistors.

    How is that voltage related to the voltage across the other branch with the single resistor? Apply Ohm's law to determine the current through that branch.

  6. May 12, 2013 #5


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    Thats ambiguous...

    1) If you mean the current through the two resistors in series is 4 amps then... Work out the voltage drop across the two in series. The same voltage drop is across the one in parallel.

    2) If you mean the total of the current in the whole circuit is 4 amps then.. Work out the equivalent resistance of (5+5)//5 and then use Ohms law to calculate the voltage drop.
  7. May 12, 2013 #6

    oops, yes, I meant that the current in the whole circuit is 4amps.
    ahh... and I completely forgot about voltage...
    I am given that ε=20V which makes the question a lot simpler now
    & thanks everyone for responding!
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