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Complicated Combination Circuit problem. PLEASE HELP

  1. Jun 6, 2010 #1
    Complicated Combination Circuit problem. PLEASE HELP!!

    1. The problem statement, all variables and given/known data


    I am suppose to create a RIVP chart with that circuit shown above.

    R1 = 10 ohms
    R2 = 14 ohms
    R3 = 9 ohms
    R4 = 11 ohms
    R5 = 5 ohms
    R6 = 9 ohms
    The voltage of the battery is 8V.

    2. Relevant equations
    The current is not given so I am assuming that I need to solve everything with Kirchhoff's rules but I'm not sure how to do that. I also noticed that the current can go in many directions.

    3. The attempt at a solution

    I know that the equations I have to use are P=IV and V=IR
    I attempted to construct my RIVP chart and there were a lot of components that I need to solve for. I am not sure how to start the problem since the current is not given.
  2. jcsd
  3. Jun 7, 2010 #2
    Re: Complicated Combination Circuit problem. PLEASE HELP!!

    You don't need to use Kirchhoff for this problem. It's possible, stepwise, to reduce all these resistors to one; and then find the main current in the cell.
    Start by replacing R4 and R6 with, say R7.
    R4 and R6 are in parallel.
    Then this R7 is in series with R5. Replace R7 and R5 with, say, R8.
    Work your way through the other resistors until there is just one left.
  4. Jun 8, 2010 #3
    Re: Complicated Combination Circuit problem. PLEASE HELP!!

    While you can use KCL and KVL here, it would be far easier to just simplify the circuit. Replace resistors in parallel and series by equivalent resistors. For example, the resistors R4 and R6 are in paralled and can be replaced by a single resistor of 4.95ohms. This way, just reduce the circuit. Finally, you will get a single resistor in series with the voltage source. Applying Ohm's Law in this case would give you the total current passing through the circuit. After that its just the matter of applying Ohm's Law to individual elements to get the voltage across them and the power dissipated by them.
    Hope this helps.
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