Below critical temperature, superconducting magnet coils exhibit what type of resistance?

• A. High resistance
• B. Variable resistance
• C. Zero resistance
• D. Infinite inductance

Answer: (C)

When a material becomes superconducting, it carries current without any energy loss. Below the critical temperature, electrons pair up into Cooper pairs and move through the lattice without scattering, so there are no dissipative processes to generate heat. That means a current can persist in a closed superconducting magnet coil indefinitely, with essentially zero resistance. This is what allows superconducting magnets to maintain their fields without resistive heating. The other ideas—high or variable resistance or infinite inductance—don’t describe the resistance behavior in the superconducting state; inductance depends on coil geometry and remains finite. So zero resistance best describes the situation.