A student places a neutral metal sphere on an insulating stand. They bring a positively charged acrylic rod close to, but not touching, the metal sphere.
While holding the rod in place, the student briefly touches the opposite side of the metal sphere with their finger to earth it.
Explain why the metal sphere is left with an overall negative charge after the earth connection is broken and the rod is removed.
47 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.