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Homework Help: Ohmic Resistance with watts

  1. May 15, 2016 #1
    1. The problem statement, all variables and given/known data
    A typical electric blanket consumes 50 W of power when operating. What is the overall resistance of the blanket if it is designed to be plugged into a standard powerpoint?
    Power = 50 watts
    Voltage = 240 v (standard powerpoint)

    2. Relevant equations
    I (current) = Voltage/ Resistance
    Power = V x I

    3. The attempt at a solution
    So we are trying to find the overall resistance:
    R = V/I
    R = 240/I
    P/V = I ?
    50/240 = I ?
    I = 0.2083333 (I don't think that looks right)
    So then, R= 240/0.2083333
    R= 1152??
    Resistance is 1152 ohms?
    These answers seem very strange to me and I am uncertain as to whether my logic is sound or not.
    If my logic is incorrect, could someone inform me of the logic of the correct way? Thanks!
  2. jcsd
  3. May 15, 2016 #2


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    2017 Award

    Staff: Mentor

    It is correct.
    Why does it seem strange to you?
  4. May 15, 2016 #3
    I wasn't sure because all the questions I had done before this had very small resistance (like 6), and I wasn't sure what an actual appliance might have in terms of resistance. Thanks for the confirmation!
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