A neutral cloth is used to rub two initially neutral rods in succession. The cloth transfers electrons carrying 6 nC6\ \mathrm{nC}6 nC of negative charge to rod P. Electrons carrying 2 nC2\ \mathrm{nC}2 nC of negative charge then move from rod Q to the cloth. No other charge is transferred. What are the final charges on the cloth and rod Q, respectively?
+4 nC+4\ \mathrm{nC}+4 nC and +2 nC+2\ \mathrm{nC}+2 nC
+8 nC+8\ \mathrm{nC}+8 nC and +2 nC+2\ \mathrm{nC}+2 nC
−8 nC-8\ \mathrm{nC}−8 nC and −2 nC-2\ \mathrm{nC}−2 nC
−4 nC-4\ \mathrm{nC}−4 nC and −2 nC-2\ \mathrm{nC}−2 nC
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.