A metal sphere, mounted on an insulating stand, is negatively charged.
State the name of the SI unit used to measure electric charge.
A smaller, initially uncharged metal sphere, also on an insulating stand, is brought close to the negatively charged sphere without making contact.
Describe how the charge distributes itself on this smaller metal sphere.
While the smaller sphere is still near the negatively charged sphere, an earthed metal wire is briefly touched against the side of the smaller sphere furthest from the charged sphere. State and explain what happens to the charge on the smaller sphere.
Explain, in terms of their atomic-level structures, why the metal wire is an electrical conductor but the plastic stand is an electrical insulator.
452 exam-style questions on CIE IGCSE Physics 4.2 Electrical quantities, covering 4.2.1a Positive and negative charge, 4.2.1b Charging by friction and detecting charge, 4.2.1c Electrical conductors and insulators, 4.2.1d Electric fields and electric field patterns, 4.2.2a Electric current, charge and measuring current, 4.2.2b Conduction in metals and the direction of current, 4.2.2c Direct current and alternating current, 4.2.3a Electromotive force, 4.2.3b Potential difference and voltmeters, 4.2.4a Resistance, 4.2.4b Resistance of a metallic wire, 4.2.4c Current–voltage graphs, and 4.2.5 Electrical energy and electrical power. Each one has a worked solution and a mark scheme showing where the marks go.