A physics student rubs two identical acrylic rods with the same piece of silk cloth. One rod is then balanced horizontally on a low-friction insulating pivot so that it is free to rotate in a horizontal plane.
Explain how the student can use the second rod to show that both rods have acquired the same type of electric charge.
47 exam-style questions on Edexcel GCSE Physics 11.1 Charging by friction. Each one has a worked solution and a mark scheme showing where the marks go.