Cell constant of the tetrapolar conductivity cell

The factors that specify the cell constant k of the tetrapolar conductivity cell are investigated. An equation to predict the value of k from the geometry of the cell is derived and validated by measuring the cell constant for different geometries in solutions of known resistivity. The constant-current method for tetrapolar resistivity measurement is used. The results show that the value of k depends only on the cell geometry and is independent of solution resistivity in the range of 30-3000 omega cm. Excellent agreement (less than 5 per cent error with a correlation coefficient of 0.99) between the predicted and the experimentally measured values of the cell constant is obtained, demonstrating that the derived expression can be used to predict the tetrapolar conductivity cell constant.