Three cylindrical specimen rods of identical length and cross-sectional area are made of copper (conductor), undoped silicon (semiconductor), and glass (insulator).
Which row correctly lists the materials in order of increasing electrical resistance at room temperature, and correctly describes the effect of a temperature increase on the resistance of the silicon rod?
Order: copper→silicon→glass\text{copper} \rightarrow \text{silicon} \rightarrow \text{glass}copper→silicon→glass
Effect of temperature rise: resistance decreases
Order: copper→silicon→glass\text{copper} \rightarrow \text{silicon} \rightarrow \text{glass}copper→silicon→glass
Effect of temperature rise: resistance increases
Order: glass→silicon→copper\text{glass} \rightarrow \text{silicon} \rightarrow \text{copper}glass→silicon→copper
Effect of temperature rise: resistance decreases
Order: glass→silicon→copper\text{glass} \rightarrow \text{silicon} \rightarrow \text{copper}glass→silicon→copper
Effect of temperature rise: resistance increases
26 exam-style questions on OCR A A Level Physics Energy, power and resistance, covering Circuit symbols, E.m.f. and p.d, Resistance, Resistivity, and Power. Each one has a worked solution and a mark scheme showing where the marks go.