A student vigorously rubs a polytetrafluoroethylene (PTFE) rod with a dry woollen cloth. The PTFE rod acquires a net static charge of −4.8 nC-4.8\text{ nC}−4.8 nC through friction.
Which of the following statements correctly describes the transfer of charge carriers and the resulting change in mass of the PTFE rod?
(Take the elementary charge to be e=1.6×10−19 Ce = 1.6 \times 10^{-19}\text{ C}e=1.6×10−19 C and the mass of an electron to be me=9.1×10−31 kgm_e = 9.1 \times 10^{-31}\text{ kg}me=9.1×10−31 kg)
The rod lost 3.0×10103.0 \times 10^{10}3.0×1010 electrons to the cloth, and its mass decreased by 2.7×10−20 kg2.7 \times 10^{-20}\text{ kg}2.7×10−20 kg.
The rod gained 3.0×10103.0 \times 10^{10}3.0×1010 electrons from the cloth, and its mass increased by 2.7×10−20 kg2.7 \times 10^{-20}\text{ kg}2.7×10−20 kg.
The rod gained 3.0×10103.0 \times 10^{10}3.0×1010 electrons from the cloth, and its mass decreased by 2.7×10−20 kg2.7 \times 10^{-20}\text{ kg}2.7×10−20 kg.
The rod lost 3.0×10103.0 \times 10^{10}3.0×1010 protons to the cloth, and its mass decreased by 5.0×10−17 kg5.0 \times 10^{-17}\text{ kg}5.0×10−17 kg.
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.