Basic DC Theory
DC CIRCUIT TERMINOLOGY
TABLE 1
Properties of Conducting Materials
r = Resistivity
Material
at 20°C-cm-W/ft (a)
Aluminum
17
Carbon
(b)
Constantan
295
Copper
10.4
Gold
14
Iron
58
Nichrome
676
Nickel
52
Silver
9.8
Tungsten
33.8
(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.
Rev. 0
Page 17
ES-02
