Superconductors

In 1911, the Dutch physicist H.K.Onnes, studied the variation of resistance of metals with temperature. He tried to cool some metals to a few Kelvins and measured their resistance. He discovered that mercury’s electrical resistance was reduced to zero at 4.2K (-269 degree Celsius). It was found that many other metals show similar behavior at certain low temperatures. This temperature is called as critical temperature. Such metals which exhibit this property is called as superconductors. In superconductors current can be transmitted without loss of energy.
Since superconductors require cooling to extremely low temperatures which were found very difficult to achieve, everyday use of superconductors was found impractical. Therefore, efforts made to search compounds that have higher critical temperatures. If superconductors are discovered which has zero resistance at room temperature, it will indeed greatly revolutionize many of the electrical devices we use today.