Physics II / The Third Law and Low Temperatures
Practice question · True or false

The entropy of a perfect crystal approaches zero as the temperature approaches absolute zero.

Hints
  1. How many arrangements does a perfect crystal have at zero temperature?
  2. Exactly one, and the logarithm of one is zero.
Show the answer

True

Why

True, this is Planck’s statement of the third law. With exactly one accessible arrangement, S=kBln1=0S = k_B\ln 1 = 0, which gives entropy a genuine absolute zero that energy does not have.

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