Textbook for Operation and Maintenance Engineer of Power and Environment Specialty of Data Center - Resistance and Resistance Law 

Table 1.1 - 1 Resistivity of materials at 20 ℃purpose
Material nameρ/ ( Ω ·m)Conductor materialsilverone point six five × 10-8copperone point seven five × 10-8aluminium
two point eight three × 10-8mild steelone point three × 10-7Resistance materialplatinumone point zero six × 10-7tungstenive point three × 10-8Manganinfour point four × 10-7Constantanfive × 10-7Nickel ferrochromeone × 10-6carbonone × 10-6
The resistance of conductor is not only related to the material property and size, but also related to the temperature. For metal conductors, the increase of temperature will intensify the thermal movement of molecules,smart rack Smart cabinet server rack network rack Network cabinet wall mounted cabinet Open Racks Frame rack accessories rack tray blank panel spacer
wire mesh cable tray Grid cable tray basket cable trayThe outer electrons of the atomic nucleus of the insulator have great attraction. raised floor access floor ALL STEEL PANEL CALCIUM SULPHATE PANEL ALUMINUM PANEL OA FLOOR T while the number of free electrons almost does not change with the temperature. The number of collisions when the charge moves will increase, and the resistance of the conductor will increase. For some semiconductors and electrolytes, the increase of the number of free charges with the increase of temperature plays a more important role than the increase of molecular thermal motion. The resistance decreases. The change of resistance with temperature can be expressed as:R2＝R 1 [ 1+ α (t2-t1 )]
Where, R1 - resistance of conductor at temperature t1;
R2 - resistance of conductor at temperature t2;α― Temperature coefficient of conductor, unit: 1/℃.Solution: The resistivity of copper can be seen from the table ρ＝ one point seven five × 10-8 Ω· m, which can be obtained from the resistance lawl 2000R＝ ρ s ＝ 1.75 × 10-8 × two × 10 －6 ＝17.5 Ω

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Textbook for Operation and Maintenance Engineer of Power and Environment Specialty of Data Center - Resistance and Resistance Law