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Calculating the Resistance of a Wire



  • The resistance of a wire depends on the cross sectional area of the wire, the length of the wire, and the resistivity of the wire material. First, the geometry of the wire is defined (wire diameter d, wire length l, and cross-sectional area A):









  • The following table allows you to select the conductor material which sets the resistivity and resistivity temperature coefficient values. Note that the unused rows of the table are hidden and can be show by clicking the button. The resistivity values are defined at a reference temperature of 20°C.


    Data source: https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity



  • Copper


  • Now the resistance of the wire can be calculated at 20°C with the result units specified as milli-Ohms (mohm):







  • The resistivity can also be approximated as a function of temperature using the resistivity temperature coefficient:





  • This allows the resistance to also be defined as a function of temperature:







  • Now that the resistance has been defined as a function of temperature, it can be plotted by specifying the temperature as a range. It can be seen that the temperature impact on wire resistance can be significant.



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