The polarity of a plastic rod and a glass rod at contact charging

Abstract

Abstract This study aims to determine the polarity of a plastic rod and a glass rod at contact charging with various materials. Contact charging often occurs when two electrically neutral materials are brought into contact, and then separated. Thus, selecting the types of material pairs has a critical role to make the contact charging more observable and measurable. This study was designed to address the astonishment of students who accidentally learned that a plastic rod can be positively charged at contact charging. What materials can cause the plastic rod to become positively charged at contact charging? This is the main research question of this study. Thus, we searched the polarity of a plastic rod and a glass rod at contact charging with various materials by using a typical laboratory electroscope and also a modern electronic electroscope. At the end of the study, it was shown that although the plastic rod is generally negatively charged at contact charging with many materials, it is positively charged at contact charging with a nylon garbage bag, a piece of nitric, or a piece of Teflon (PTFE). In addition, the glass rod is generally positively charged at contact charging with many materials except the human hair.