How to Demonstrate the Voltage on a charged object in Physics Laboratory

Abstract

Common Objects like a comb or a pen get charged when rubbed against something like human hair or garment clothing. Charged objects exhibit noticeable attractive or repulsive force lifting small pieces of paper or pushing/pulling a suspended light object charged with the same/opposite(uncharged) polarity respectively. This indicates the strong electrical nature of charged objects. Flashes due to spark between oppositely charged objects can be seen in total darkness. Implying a large potential difference between these charged objects which is not possible at lower voltages. This article describes a method to measure the voltage on commonly charged objects with respect to earth using simple instrumentation based on capacitors and CMOS voltmeter. Once the potential difference is known the average charge on the object can be calculated as well. The article also suggests a simple femto-farad capacitance meter for electrostatics work.