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The Accuracy of Kelvin

  1. May 4, 2015 #1
    Why is the Kelvin scale more accurate than the Celsius scale when a change of 1K is equal to a change of 1°C? It's something I've always wondered about but never looked into.

    (Apologies if the answer is incredibly simple. I'm still very new to the world of physics :smile:)
  2. jcsd
  3. May 4, 2015 #2


    Staff: Mentor

    Accuracy and precision are properties of the measuring device, not the measurement scale. You could have an accurate thermometer marked in Celcius and an inaccurate thermometer marked in Kelvin.

    The advantage of Kelvin over Celsius is that the zero point in Kelvin is absolute zero while the zero point in Celsius is just the freeing point of water. When doing thermodynamics the formulas become simpler when 0 is set to absolute zero.
  4. May 4, 2015 #3
    Ah, that makes sense. I definitely see why Kelvin is advantageous.
    Thanks a lot!
  5. May 4, 2015 #4


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    Where did you get the idea that the Kelvin scale is more accurate than the Celsius scale?

    We tend to use the Kelvin scale in many situations in physics not because it is more accurate. But rather, that is considered, in thermodynamics, as the "absolute" scale. It has nothing to do with accuracy, as DaleSpam stated.

  6. May 4, 2015 #5
    My physics teacher told the class it was more accurate, which I knew didn't make sense since 1K and 1°C are equal in size.
    Thanks for clearing things up for me. That saved me from a lot more confusion!
  7. May 4, 2015 #6


    Staff: Mentor

    Either you heard wrong, or that teacher has a very poor understanding of physics.
  8. May 4, 2015 #7


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    The K scale makes much more sense, in any case, as it starts at Zero. Any Physics lab on another planet could easily choose the same starting point. Of course, the step size would still be a bit arbitrary. Some (just one) other defined temperature would need to be chosen and they we could converse with them about Thermodynamics with no trouble.
    The fact that we could never actually get to 0K, is a mere detail. . . . .
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