This shows you the differences between two versions of the page.
Both sides previous revision Previous revision Next revision | Previous revision | ||
ec_theory [31/03/2015 09:47] pieter |
ec_theory [11/04/2018 11:51] (current) pieter |
||
---|---|---|---|
Line 12: | Line 12: | ||
The units of measurement used to describe conductivity and resistivity are quite fundamental and are frequently misused. Once the units are known, various waters can be quantitatively described. | The units of measurement used to describe conductivity and resistivity are quite fundamental and are frequently misused. Once the units are known, various waters can be quantitatively described. | ||
- | The basic unit of resistance is the familiar Ω (Ohm). Conductance is the reciprocal of resistance, and its basic unit is the Siemens (S). In discussions of bulk material, it is convenient to talk of its specific conductance, | + | The basic unit of resistance is Ohm. Conductance is the reciprocal of resistance and its basic unit is Siemens (S). In discussions of bulk material, it is convenient to talk of its specific conductance, |
+ | <WRAP center round box 60%> | ||
{{pictures/ | {{pictures/ | ||
// | // | ||
+ | </ | ||
+ | |||
Users of ultra pure water prefer to use the resistivity unit of //MΩ.cm//, because the measurement in this unit tend to spread the scale out in the range of interest. These same users frequently use //kΩ.cm// when dealing with less pure water such as tap water. | Users of ultra pure water prefer to use the resistivity unit of //MΩ.cm//, because the measurement in this unit tend to spread the scale out in the range of interest. These same users frequently use //kΩ.cm// when dealing with less pure water such as tap water. | ||
Line 31: | Line 34: | ||
Since the conductivity of a solution varies with temperature, | Since the conductivity of a solution varies with temperature, | ||
+ | <WRAP center round box 60%> | ||
**G = C x cc / (1 + a(t -tr))** | **G = C x cc / (1 + a(t -tr))** | ||
+ | </ | ||
+ | |||
in which: | in which: |