A student rubs a plastic rod with a dry cloth, giving the rod a negative electrical charge. When this charged rod is brought near a lightweight sphere suspended from an insulating thread, the sphere is attracted towards the rod. What can be concluded about the electric charge on the sphere?
The sphere must have a positive charge (q>0q > 0q>0).
The sphere must be neutral (q=0q = 0q=0).
The sphere is either positively charged or neutral (q≥0q \ge 0q≥0).
The sphere is either negatively charged or neutral (q≤0q \le 0q≤0).
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.