Metals are usually used to conduct electricity because electrons (the particles that make up electrical current) can move around freely in metal. For example, copper wires are used in houses to distribute electrical current to various appliances. This electrical current is produced by the flow of free electrons inside the metal wire. In a normal conductor the electrons collide with what is called a “metal lattice” — a grid of copper or aluminum atoms making up the solid metal wire. The collisions take away some of the energy from the electrons to produce heat, which is why some materials might heat up when they conduct electricity. This phenomenon is an obstacle, or “resistance” to how much current can flow through the wire.

Superconductor materials are usually metal alloys (combinations of metals) cooled to very low temperatures. In a superconductor, instead of working in solo, electrons travel in pairs. Those pairs have the unusual property that they can move through the metal wire with practically no collisions with surrounding metal atoms. This means that the electrical resistance of the superconductor is almost zero! Much larger quantities of current can flow through the same wires without causing any heat loss due to collisions.

The major uses of superconductors are for devices that use electromagnets. In an electromagnet, electrical current is used to produce magnetic fields. When a normal conductor is used, there are limits to how strong a magnet can be because of the electrical resistance and heat dissipation in a normal conductor. However, if you use a superconductor, much more powerful magnets can be built. For example, medical scanners, like the MRI (Magnetic Resonance Imaging) or NMR (Nuclear Magnetic Resonance) need very powerful electromagnets. These systems are used in radiology to get pictures of the organs inside the human body. Superconductors are also used in mass spectrometers, a special device used to investigate the composition of matter, and in particle accelerators, where powerful electromagnets accelerate high energy beams of particles so they collide with matter to produce exotic new particles. Other applications that we might see soon are magnetic levitation trains and energy transmission and storage.

This answer was written by Jean Deslauriers, an Ask Us Expert.

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