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Muthumanimaran
- 81
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Homework Statement
A great deal of effort has been expended to find “high temperature superconductors”: materials that are superconductors at temperatures higher than the boiling point of liquid nitrogen (77 K). Most of the older superconductors had to be operated with liquid helium (boiling point 4.2 K) as the cooling fluid. To estimate the savings possible in operating costs through the use of the “high temperature” superconductors, calculate the minimum work needed to compensate for a heat leak of 1 kJ into the superconductor for both “high temperature” superconductors and the older ones. Assume that the ambient temperature is 300 K.
Homework Equations
First law of Thermodynamics
The Attempt at a Solution
Minimum work needed to compensate heat leak, so the first law of thermodynamics says
so
The specific heat for Liquid Nitrgoen is
for ordinary superconductor, for liquid helium
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