What is a defining property of superconductors?

What is a defining property of superconductors?

• A. Substances that generate energy
• B. Substances that conduct only alternating current
• C. Substances that become insulators at high temperature
• D. Substances with zero resistance

Answer: (C)

Zero electrical resistance below a certain critical temperature defines a superconductor. When cooled into this regime, electrons pair up into Cooper pairs and move through the material without scattering, so an electric current can flow without any energy loss as heat. This is why superconductors can sustain persistent currents. Another hallmark is the Meissner effect—the expulsion of magnetic fields from the interior—which further distinguishes superconductors from ordinary conductors. So the defining property is their zero resistance, not energy generation, insulating behavior at high temperature, or conduction that’s limited to alternating current.

Zero electrical resistance below a certain critical temperature defines a superconductor. When cooled into this regime, electrons pair up into Cooper pairs and move through the material without scattering, so an electric current can flow without any energy loss as heat. This is why superconductors can sustain persistent currents. Another hallmark is the Meissner effect—the expulsion of magnetic fields from the interior—which further distinguishes superconductors from ordinary conductors. So the defining property is their zero resistance, not energy generation, insulating behavior at high temperature, or conduction that’s limited to alternating current.