Physlet Illustration: Thermal Conductivity

 

 

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Length = cm Area = cm2 Temperature= oC
A bar of square cross-section, variable between 1 and 36 cm2, is in contact at one end with a cold temperature reservoir and at the other end with a hot reservoir.  You may change the length of the bar (from 5 cm to 40 cm) and temperature (from 10o to 300o) of the hot reservoir, as well as the area of the bar.  The heat transfer is plotted as a function of time on the right.  What is the thermal conductivity of the bar?

Hints

  1. Measure the temperature gradient by "measuring" the temperature at several points along the bar with the thermometer provided.  
  2. Calculate the heat transfer per second from the graph of heat transfer versus time.
  3. Change the length of the bar.  How does it affect the heat transfer?
  4. Change the area of the bar.  How does it affect the heat transfer?
  5. Change the temperature of the hot reservoir.  How does it affect the heat transfer?

Reference

See Walker, Section 16-6

Illustration written by Chuck Niederriter