Basic DC Theory
DC CIRCUIT TERMINOLOGY
Properties of Conducting Materials
r = Resistivity
at 20°C-cm-W/ft (a)
(a) Precise values depend on exact composition of material.
(b) Carbon has 2500-7500 times the resistance of copper.
Temperature Coefficient of Resistance
Temperature coefficient of resistance, a (alpha), is defined as the amount of change of the
resistance of a material for a given change in temperature. A positive value of a indicates that
R increases with temperature; a negative value of a indicates R decreases; and zero a indicates
that R is constant. Typical values are listed in Table 2.