Super Conductors Super conductors are those elements or compounds, which below a certain temperature, exhibit no resistance to the flow of electrons. This temperature is called the critical temperature. This temperature is different for different substances. A second factor affecting superconductivity is the presence of a magnetic field. For every temperature below the critical temperature there is a critical magnetic field strength above which the substance looses its superconducting property. The third factor affecting a material's superconductivity is current density. For each temperature below critical temperature and each magnetic field strength below critical, there is a critical current density above which the material is not superconductive. Unlike the other two factors, critical current density can be increased by proper materials processing . When superconductivity was first discovered it was thought to exist only within about 25¡ of absolute zero. (25¡ Kelvin or 248¡ Celsius or 415¡ Fahrenheit.) These temperatures were obtained through the use of liquid helium at about 4.2¡ Kelvin. Recently, materials have been discovered which are superconductive at temperatures above that of liquid nitrogen (77¡ Kelvin). The major drawback to these higher temperature superconductors are low critical magnetic field and low current density at liquid nitrogen temperatures. However, at the temperature of liquid helium they do have higher critical magnetic fields than earlier known super conductors. Until now no wide spread commercial use of superconductors has occurred due to the high cost of liquid helium. If higher temperature superconductors can be developed and the problems of low critical magnetic field and current density solved, then they might become economically feasible due to the lower cost of liquid nitrogen.Some possible uses include energy generation, transmission and storage. Other applications exist in the fields of computers and electronics. Much research and development will be necessary in the near future to realize these possibilities.