An Apparatus to Measure Surface Electric Potential of Electrets

Abstract

A simple and low-cost apparatus to nondestructively measure the surface electric potential of electrets was built and tested. The apparatus consisted of a vibrating electrode connected to an oscilloscope and a fixed electrode on which a sample ceramic pellet was placed. The fixed electrode was connected to a variable voltage supply. Measurement is achieved by adjusting the bias voltage so that output sinusoidal AC wave observed on the oscilloscope becomes null.