A metallic wire is connected across the terminals of a DC power source, establishing a conventional current from the positive terminal to the negative terminal through the wire. What are the charge carriers responsible for this current in the wire, and in which direction do they travel?
Free electrons moving from the negative terminal of the power source to the positive terminal
Free electrons moving from the positive terminal of the power source to the negative terminal
Positive metal ions moving from the positive terminal of the power source to the negative terminal
Positive metal ions moving from the negative terminal of the power source to the positive terminal
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.