When electrons flow through a conductor they collide with atoms and electrical energy is gradually lost in the form of heat. This process is called electrical resistance. However, when some substances become very cold, all electrical resistance is lost and the current flows freely without loss of energy. These substances are called superconductors. Their use allows some devices to work faster and more efficiently than ever before. Because of the difficulty in keeping superconductors cold, their use is limited. In the future, superconductors may be used to make efficient computers.

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