already discusses the question but I did not understand the marked answer. It does not outright say whether a superconductor has zero resistance or not.   Do superconductors have exactly zero resistance, nearly zero resistance or does the concept of resistance as we know it break down when it comes to superconductors? Or is the question senseless because of experimental errors?
It is known that a superconductor is a material with electrical resistance zero. My question is, it is exactly zero, a theoretical zero, or for practical realistic reasons it is effectively zero?
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