The cell constant of a given conductivity cell is obtained by measuring the resistance \((R)\) (or the conductance) of a standard solution whose conductivity \(\left(f_{d}\right)\) is accurately known by using Wheatstone's bridge. For this purpose, \(\mathrm{KCl}\) solution of accurately known conductivity is used.
\(k_{K C l}=\frac{1}{R_{K C}} \times \frac{l}{a}\) where \(\frac{l}{a}\) is a cell constant, represented by b.
$$
\begin{aligned}
&\therefore \text { КKल }=\frac{b}{R_{\text {सC }}} \\
&\text { or } \mathrm{b}=\kappa_{\text {KCO }} \times \mathrm{R}_{\text {KCI }}
\end{aligned}
$$
For example, the conductivity of \(0.01 \mathrm{M} \mathrm{KCl}\) is \(0.00141 \Omega^{-1} \mathrm{~cm}^{-1}\left(5 \mathrm{~cm}^{-1}\right) .\) Hence by measuring \(R K C l\) the cell constant \(b\) can be obtained.
