A magnet is placed on the superconducting disk. Because the superconducting disk repels the magnetic induction line, there is repulsive force between the superconducting disk and the magnet, and the magnet is suspended above the superconducting disk. This kind of superconducting suspension can be used in engineering technology, and superconducting suspension train is an example. Let the train float off the track, so that the resistance of the train is greatly reduced, and the speed of "flying" along the track can reach 500 km/h. After the discovery of high-temperature superconductors, the superconducting state can appear in the temperature range of liquid nitrogen (higher than-196 degrees), and the superconducting suspension device is simpler and the cost is greatly reduced. Southwest Jiaotong University in China successfully developed the HTS suspension experimental vehicle in 1994.

Superconducting phenomenon

19 1 1 year, Dutch scientist Anis found that when the temperature dropped to MINUS 269 degrees, the resistance of mercury actually disappeared! Figure 1 reproduces the experimental curve at that time. The disappearance of resistance is called zero resistance. The so-called "resistance disappearance" only means that the resistance is less than the minimum measurable resistance of the instrument. Some people may think: if the sensitivity of the instrument is further improved, will the resistance be measured? This problem can be solved by "continuous current" experiment.

The loop composed of normal conductors has resistance, which means the loss of electric energy, that is, the conversion of electric energy into heat. In this way, if there is no power supply to continuously replenish energy to the loop, all the electric energy in the loop will be consumed in a very short time (in microseconds), and the current attenuation will be zero. If the loop has no resistance, there will naturally be no loss of electric energy. Once the current is excited in the loop, it can continue to exist without any power supply to replenish energy to the loop.