How do cryogenic temperatures affect superconductivity?
The electrical resistance of many, but not all, metals and metalloids decreases abruptly to zero at temperatures of a few degrees Kelvin. If an electric current is introduced into a ring of metal that has been cooled to the superconductive state, the current will continue to travel around the ring and may be detected hours later. What are some applications for cryogenics technology? One of the most important applications of this technology is the large-scale production of liquid nitrogen and liquid oxygen from air. Liquid oxygen has a number of uses, including rocket engines, cutting and welding torches, life support in space and deep-sea vehicles, and blast furnace operations. Liquid nitrogen is used in the manufacture of ammonia for fertilizers, as well as in the rapid cooling of frozen foods to prevent damage to cell tissues. Nuclear physicists require liquid hydrogen and liquid helium in particle detectors, particle accelerators, and nuclear fusion research. Infrared devices, maser
