The role of instrumentation in the process of modeling real capacitors

A laboratory experiment for the introductory electrical circuit course is presented. The experiment consists of the measurement of real commercial capacitors' impedance using a relatively low-cost impedance meter, and further analysis on two levels. First, when results follow well the conventional impedance expression of an ideal capacitor, the capacitance can be determined accurately. Second, when deviations are found, the more advanced framework of equivalent circuit representation has to be used. This representation is discussed for the particular case of capacitors with DC leakage. This experimental approach explicitly emphasizes the role of electrical models in engineering and suggests how to use instrumentation to validate them.