15 1.5 Conductors, Insulators and Semiconductors – P3 Other Factors that Affect Resistance  Resistivity – the resistance of a specified volume of an element or compound CM-  /ft – Circular-mil ohms per foot  -cm – Ohm-centimeters  Length  Cross-Sectional Area  = resistivity (greek letter, rho) ℓ = length A= cross-sectional area Example Calculate the resistance of a 25 cm length of copper that has a cross- sectional area of 0.04 cm 2.
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