Calibration of a reference capacitor using general-purpose precision instruments

A method for the accurate calibration of a reference capacitor is presented that relies on instruments often available in educational and industrial laboratories. These are a reference resistor, an inductive voltage divider and a multiple period counter. While the principles are elementary, precautions must be taken if an uncertainty of 100 p.p.m. or less is to be achieved. Sources of error are therefore analysed. It is shown how errors can be reduced by a system of screening and by corrections derived from simple preliminary measurements.