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Homework Help: Temperature dependence of resistors help please!

  1. Feb 16, 2009 #1
    1. The problem statement, all variables and given/known data

    A toaster with a Nichrome heating element has a resistance of 150 omega at 20degrees Celsius and an initial current of 2 A. When the heating element reaches its final temperature, the current is 1.73 A. What is the final temperature of the heating element?

    2. Relevant equations

    Not sure if they will help but...

    (for the equations below i will use p as rho)

    R = (p) (L/A)

    temperature coefficient of resistivity, alpha = ((p - p0)/p0)/ (T - T0)

    3. The attempt at a solution

    The only equation relating to the temperature of resistors was the temperature coefficient but I'm not sure how to use it. Thanks for the help!!
  2. jcsd
  3. Feb 16, 2009 #2


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    You need the temperature dependence of the resistivity of nichrome.
    Assuming the voltage is the same then from the current you can work out the resistance change and from the temperature coefficent - the temperature change,
  4. Feb 16, 2009 #3

    I'm not sure what you mean here, could you expand a little please? Thanks.
  5. Feb 16, 2009 #4


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    The resistivity of nichrome (like any other metal) depends on it's temperature
    You can look up the value in a data book or on the web.
    Then you can use this and the resistance change to find the temperature.
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