Why would a conductor resistance?

Water flow in the pipe, under the influence of friction resistance. When free charge directional movement form current in the conductor, should also be impeded. Inside the metal conductor, already exist and positively charged ions, atoms and free electrons. Under the action of external power, when free electrons in the conductor interior do directional movement, can arrange with the rule of atoms and positive ions collide, hindered the directional movement of electrons. The role of the conductor this block electricity pass through are called the resistance of the conductor.

the experimental results show that the resistance of the conductor changes with temperature changes. When temperature increases, the resistance of the metal will be increased. In the light bulb filament ( Tungsten wire) , no light at the temperature only a few degrees, the resistance is small, light at the 2 000 ℃, the filament resistance will increase many times. Bulb with tungsten wire is easy to break after a long time, tungsten wire is broken but mostly occur in the moment when turn on the light, that's because just turn on the light when the filament temperature is not higher moments, its resistance is small, with the help of the filament current is much bigger than when luminescence. In 1911, the Dutch physicist Leonard, conducted an experiment: he will mercury cooled to minus 40 ℃ below, discovered that mercury resistance decreases. When the temperature dropped to 4. 173K( - 268. 977℃) He was surprised to find that the resistance of the mercury suddenly disappeared.

at extremely low temperature condition, the mercury in the resistance of the 'missing', and the findings had hit the scientific community, has attracted great attention. Subsequently found that there are some metals and alloys in the temperature dropped to a certain value, the resistance is suddenly disappeared. The resistance is the sudden disappearance of phenomenon is called 'superconducting phenomenon', called with superconductivity material superconductors.

the discovery of superconductivity, opened up a new field to save electrical energy exploration. Scientists are trying to find the critical high temperature superconducting material, actual production services.