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1 markDesign and Use of Thermometers

CAPE Physics Unit 1 · 2009 · Paper 2 · Question 3(b)(i)

Thermodynamic temperature T is given by T = Ttr * (PT / Ptr), where Ttr is the thermodynamic temperature of the triple point of water, and PT and Ptr are gas pressures at temperature T and the triple point, extrapolated to zero pressure. Ttr is chosen as 273.16 K.

The value of Ttr is chosen to be 273.16 K. Why is this particular number used?

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Other parts of this question

  1. 3(a)Calculate the centigrade temperature of the hot water.[3 marks]
  2. 3(b)(ii)a)Complete Table 2 by filling in the missing values of PT/Ptr.[1 mark]
  3. 3(b)b)Give ONE reason why the values of PT/Ptr are NOT constant.[1 mark]
  4. 3(c)On the grid provided on page 9, plot a graph of PT/Ptr against Ptr, starting the Ptr scale at 0.[4 marks]
  5. 3(d)Read off the intercept on the PT/Ptr axis of your graph.[1 mark]
  6. 3(e)Using your result in (d), deduce an accurate value of the thermodynamic temperature T.[2 marks]
  7. 3(f)Calculate the temperature found in Part (e) on the Celsius scale.[1 mark]

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