Impedance bridges, alternating-current

The standard method to measure impedance values as a function of the potential is the Wheatstone bridge (Figure 4.13). The electrochemical cell is placed in one branch of the bridge. In the second branch a variable resistance and a variable capacitance are placed. An alternating current is applied to a potentiostat. In the reference circuit, capacitance and resistance are varied until the bridge current, measured with an AC instrument or an oscilloscope, is zero. 

R. D. Armstrong, W. P. Race, and H. R. Thirsk [ 1968] Determination of Electrode Impedance over an Extended Frequency Range by Alternating-Current Bridge Methods, Electrochim. Acta 13,... 

For the experimental determination of the impedance of a measured system the alternating current bridge is the most accurate method. This method, utilizing a... 

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