A rubber guide rubs against one edge of a wide nylon conveyor belt. Both objects are neutral before the belt starts moving. The belt is stopped and a charge detector is used immediately.
| Place tested | Detector reading |
|---|---|
| edge of belt that rubbed against the guide | positive |
| rubber guide | negative |
| opposite edge of belt, which did not touch the guide | no charge detected |
Which explanation of the detector readings is correct?
Electrons moved from the contacted edge of the nylon belt to the rubber guide; the electron shortage remained at that edge because nylon has almost no free charges.
Electrons moved from the rubber guide to the contacted edge of the nylon belt; they stayed there because electrons are fixed inside atomic nuclei.
Rubbing created positive charge at the contacted edge of the nylon belt and negative charge in the rubber guide; the nylon then stored the new charge.
Electrons shifted within both objects during rubbing without crossing between them; this left the belt edge and rubber guide with opposite overall charges.
91 exam-style questions on Edexcel GCSE Physics 11.1 Charging by friction, covering 11.1.1 Charging insulators by friction, 11.1.2 Forces between charges, 11.1.3 Electrostatic phenomena, and 11.1.4 Earthing and removing charge. Each one has a worked solution and a mark scheme showing where the marks go.