sentence2_structure: You<>call<>materials able to conduct electricity with 100% efficiency
sentence1: Superconductors can carry large amounts of current without energy-wasting resistive losses, thus they have the potential of increasing the efficiency of electric power transmission from power stations.
sentence2: You call materials able to conduct electricity with 100% efficiency, meaning that no energy is lost during the electrical transmission, superconductors.
question: What do you call materials able to conduct electricity with 100% efficiency, meaning that no energy is lost during the electrical transmission?