In a factory, dry plastic pellets slide along a polythene delivery chute. Friction causes the chute to become positively charged, and some uncharged pellets cling to its surface. The chute is fixed to an earthed metal frame.
The factory fits a fine water spray that keeps the surface of the chute damp. After this, far fewer pellets cling to the chute.
Suggest why far fewer pellets cling to the chute when its surface is damp.
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.