Although the resistor is defined as: 1 volt voltage generates a power generation of 1 Euro resistance; but the voltage, current is not a factor in determining the resistance.
The resistance value of the resistance element is generally related to the temperature, and is also related to the length of the conductor, the cross-sectional area, and the material. In the case where the conductor length, the cross-sectional area, the material is constantly, the resistance of the resistance of (metal) will increase the resistance value of the ambient temperature, which is a positive temperature coefficient resistance; other semiconductor materials are opposite, such materials with the environment The increase in temperature is reduced, which is a negative temperature coefficient resistor.
In various metal conductors, the conductivity of silver is best, but there is still a resistance. At the beginning of the 20th century, scientists found that when some substances were at a very low temperature, such as aluminum below 1.39K (-271.76 ° C), lead below 7.20 k (-265.95 ° C), and the resistance becomes zero. This is superconducting phenomenon, and it can be superconducting material with materials with this performance. Some "high temperature" superconducting materials have been developed, which can be reduced to zero at 100K (-173 ° C) resistance.
We often need to set a variety of resistance to limit the resistance of various resistance to limit streams, shunt, step-down, and partial pressure. However, in some occasions, the smaller the resistance is, such as power generation, transportation, storage power, etc., the smaller the resistance, and if the superconducting material can be used, it can greatly reduce the electric energy caused by the resistor. Consume. If the superconducting material is used in the actual, manufacturing electronic components, because there is no resistance, it is not necessary to consider the problem of heat dissipation, the element size can be greatly reduced, and the miniaturization of electronic devices will bring a lot of benefits to humans.