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Homework Help: Circuit Problem with Wattages instead of Resistances

  1. Apr 15, 2010 #1
    1. The problem statement, all variables and given/known data
    there is a 110-V battery serving as a voltage source, and the circuit goes like:

    from the battery, there is a 100-Watt bulb connected, then the circuit branches into two parallel wires each with 100-Watt bulbs, then the wires rejoin and lead back to the battery, find everything you can.


    2. Relevant equations
    P=VI
    R=V/I


    3. The attempt at a solution
    I don't even know where to begin, I tried finding the current but realized that I needed the Power too to solve, and I don't know how to get the power either.
     
  2. jcsd
  3. Apr 15, 2010 #2

    Borek

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    Staff: Mentor

    Imagine a single 100W bulb connected directly to 110V battery. Can you calculate current?
     
  4. Apr 15, 2010 #3
    Try to figure out the effective resistance of the circuit first.
     
  5. Apr 15, 2010 #4
    it's 3R/2 but i still don't know R
     
  6. Apr 15, 2010 #5
    Consider a single light bulb on a simple circuit. That's what the 100W power rating is (generally) defined for.
     
  7. Apr 15, 2010 #6

    Borek

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    Staff: Mentor

    As if I were reading my earlier post :grumpy:
     
  8. Apr 15, 2010 #7
    Sometimes people need to be told more than once.
     
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