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Homework Help: Finding Maximum Voltage of Resistors

  1. Apr 21, 2015 #1
    1. The problem statement, all variables and given/known data

    A 2.44-kΩ and a 4.92-kΩ resistor are connected in parallel; this combination is connected in series with a 1.12-kΩ resistor. If each resistor is rated at 1/2 W, what is the maximum voltage that can be applied across the whole network?

    2. Relevant equations

    3. The attempt at a solution
    I solved for the equivalent resistance.
    I converted the kΩ to Ω and used the equation for parallel resistors
    1/R1,R2 = (1/R1)+(1/R2) = 1/2440 + 1/4920 = 6.1308E-4
    R1,2 = 1/6.1308E-4 = 1631.086957 Ohms
    then R123 = R1,2+R3 = 1631.086957+1120 = 2751.086957 Ohms
    Then I used P=V^2/Req
    V=23.6643 V (which should be the maximum voltage since parallel resistors have the same voltage throughout)
    But it's wrong and I'm not sure where I messed up?
  2. jcsd
  3. Apr 21, 2015 #2
    Recheck your final calculation. I get an answer of 37.09 using 1/2 = V^2/2751.086957.
  4. Apr 21, 2015 #3
    Oh that was a calculation error that I made, say it is 37.0883 V but that isn't the right answer. Am I missing some sort of equation for the maximum voltage once I figure out the V from P=V^2/R ?
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