DC CIRCUIT TERMINOLOGYBasic DC TheoryResistivityResistivity is defined as the measure of the resistance a material imposes on current flow. Theresistance of a given length of conductor depends upon the resistivity of that material, the lengthof the conductor, and the cross-sectional area of the conductor, according to Equation (2-1).R = (2-1)rLAwhereR = resistance of conductor, Wr= specific resistance or resistivity cm-W/ftL = length of conductor, ftA = cross-sectional area of conductor, cmThe resistivity r (rho) allows different materials to be compared for resistance, according to theirnature, without regard to length or area. The higher the value of r, the higher the resistance.Table 1 gives resistivity values for metals having the standard wire size of one foot in length anda cross-sectional area of 1 cm.ES-02 Page 16 Rev. 0

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