A lightweight plastic pointer is balanced on an insulating pivot so that it can turn freely. A positively charged roller can be moved close to the pointer without touching it.
Which observation is conclusive evidence that the pointer has a positive charge?
The pointer turns away from the positively charged roller.
The pointer turns through a smaller angle when the roller is moved further away.
The pointer turns through a larger angle after the roller is given more positive charge.
The pointer begins to turn before the positively charged roller touches it.
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.