A superconducting ring can carry a current for an indeﬁ nite length of time. Isn’t this a perpetual motion machine, which violates the ﬁ rst or second law of thermodynamics? Explain.

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Tamoni5e · Accepted Answer

Perpetual motion machine is a kind of machine which can do work without any energy input.A Superconductor is an hypothetical material which offers zero resistance. The entropy change in a superconducting material is zero as it is a highly ordered material.From Second law of thermodynamics:  △  S  =            △      Q        T      0  =            △      Q        T      △  Q  =  0From first law of thermodynamics:  △  Q  =  △  U  +  △  W    0  =  △  U  +  △  W    △  W  =  −  △  USince internal energy of a superconductor is constant.  △  U  =  0Then,Work done,   △  W  =  0But, in this case the superconductor is carrying the current for indefinite amount of time so work done can&#039;t be zero. So it is violating the First Law of Thermodynamics.

A superconducting ring can carry a current for an indeﬁ nite length of time. Isn’t this a perpetual motion machine, which violates the ﬁ rst or second law of thermodynamics? Explain.

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