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Homework Help: Resistance and Temperature(isn't this right?)

  1. Oct 13, 2008 #1
    1. The problem statement, all variables and given/known data

    A platinum resistance thermometer has a resistance of 200 when placed in a ice 0◦C
    bath and 280 when immersed in a crucible containing a melting substance. What is
    the melting point of the substance? The temperature coefficient of the platinum is
    0.00392(◦C)−1. Answer in units of ◦C.


    2. Relevant equations

    R = r [1 + a(T - t)]

    3. The attempt at a solution

    This looks like such a simple problem, just plug and chug, but I keep getting the wrong answer.

    280 = 200 [1 + 0.00392(T - 0)]
    1.4 = 1 + 0.00392T
    0.4 = 0.00392T
    T = 102.04
     
  2. jcsd
  3. Oct 13, 2008 #2

    LowlyPion

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    Homework Helper

    The online calculator would seem to agree with your answer:
    http://hyperphysics.phy-astr.gsu.edu/hbase/electric/restmp.html#c3
     
  4. Oct 13, 2008 #3
  5. Oct 13, 2008 #4

    LowlyPion

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    Homework Helper

    Perhaps the significant figures is in error? They would want only 102 C?
     
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