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Homework Help: Power Consumption #2

  1. Nov 27, 2011 #1
    1. The problem statement, all variables and given/known data
    A toaster with 18Ω is conducted to a 220 volt source. What is the power consumed by the toaster.

    2. Relevant equations

    3. The attempt at a solution
    P= 3,960
  2. jcsd
  3. Nov 27, 2011 #2


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    Homework Helper

    You have multiplied the resistance by the voltage, the formula you stated was for current by voltage.
    You need to incorporate Ohms law.
  4. Nov 27, 2011 #3
    Although it seems annoying, it helps to keep re-writing your units to check if your answer has the correct dimensions.

    P = IV is a good equation to use, but here you aren't given the current; you're given the resistance of the toaster. Try using Ohm's law to rearrange the equation for power and find an equation whose knowns are already given.
  5. Nov 27, 2011 #4
    What do you mean?
  6. Nov 27, 2011 #5
    Ohm's law relates the resistance, current and voltage of a circuit. Knowing this, you can solve for any one (resistance, current, voltage) and put it in terms of the other two.
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