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How does electrical resistance in a normal conductor differ from resistance in a superconductor?

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Figure 1: Specific heat in the normal (Cen) and superconducting (Ces) states of a classic superconductor as a function of absolute temperature. The two functions are identical at the transition temperature (Tc) and above Tc. — superconductivity Figure 1: Specific heat in the normal (C_en) and superconducting (C_es) states of a classic superconductor as a function of absolute temperature. The two functions are identical at the transition temperature (T_c) and above T_c.

In a normal conductor, electrical resistance arises because charge-carrying electrons collide with atoms and other electrons within the material's structure. These collisions cause the electrons to lose energy, which is dissipated as heat, meaning a constant voltage is required to maintain a steady current.12

In contrast, a superconductor undergoes a transition when cooled below a specific transition temperature, at which point it loses all electrical resistance. In this state, electrons form Cooper pairs that move in a correlated manner. Because of the quantum mechanical nature of these pairs, they move through the material without losing energy to the medium through collisions or phonon excitations. Consequently, once an electric current is established in a superconductor, it can flow indefinitely without an applied voltage. If the material is warmed above its transition temperature or subjected to a sufficiently strong magnetic field, the Cooper pairs separate, and the material reverts to its normal, resistive state.345216