QUESTION 15 Which one of the following statements cancerning superconductors is false? Below its critical temperature, the resistivity of a supercanductor is zero
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. Critical temperatures for some supercanductors erceed 100 K . All materials are superconducting at tempiratures near absolule zero kelvin. A constant current can be mhaintained in a superconducting ring for several years without an emf. Superconductors are perfect conductors.