Electromagnetics I
Ch 10
Loc 10.3

Conductivity of Some Common Materials

The values below are conductivity

for a few materials that are commonly encountered in electrical engineering applications, and for which conductivity emerges as a consideration.

Note that materials in some applications are described instead in terms of resistivity, which is simply the reciprocal of conductivity.

Conductivity may vary significantly as a function of frequency. The values below are representative of frequencies from a few kHz to a few GHz. Conductivity also varies as a function of temperature. In applications where precise values are required, primary references accounting for frequency and temperature should be consulted. The values presented here are gathered from a variety of references, including those indicated in “Additional References” at the end of this section.

Free Space (vacuum):

Material	$\sigma$ (S/m)
Copper
Gold	$4.4\times 10^7$
Aluminum	$3.7\times 10^7$
Iron	$1.0\times 10^7$
Platinum	$0.9\times 10^7$
Carbon	$1.3\times 10^5$
Silicon	$4.4\times 10^{-4}$

Table 10.3.1: Commonly encountered elements:

Water exhibits

ranging from about

S/m for highly distilled water (thus, a very poor conductor) to about 5 S/m for seawater (thus, a relatively good conductor), varying also with temperature and pressure. Tap water is typically in the range 5–50 mS/m, depending on the level of impurities present.

Soil typically exhibits