Measurement of Conductance of a Solution:

The Principle of the Wheatstone bridge discussed above could be used to measure the conductance of solutions.  Therefore, the subsequent considerations must also be kept in mind:

i) Because a direct current would polarize the electrodes within the conductivity cell through electrolyzing the solution to avoid polarization an alternating current (ac) source of power must be used in place of a dc source (battery) commonly ac voltages of 3-6 volts along with frequency of 50 Hz or 1000 Hz used across points A and C of Figure.

ii) A suitable conductivity cell (with electrodes dipped in the solution) is located among points C and D. Therefore, R_x represents the resistance of the conductivity cell.

iii) Because, the cell also acts like a small capacitor (C_x), and to balance its capacitive resistance a variable capacitor, C_B, must be inserted within the bridge.

iv) The balance indictor (BI) might be an ac galvanometer.