A metal wire of a fixed volume is drawn out to have various diameters ddd, resulting in different resistances RRR.
Which of the following relationships between R R\,R and d d\,d is correct?
RRR is inversely proportional to ddd
RRR is inversely proportional to d2d^2d2
RRR is inversely proportional to d3d^3d3
RRR is inversely proportional to d4d^4d4
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.