An electrical engineer chooses materials for power cables.
Cables inside homes have copper wires covered in PVC, a polymer. Overhead power lines are made of aluminium wires wound around a steel core. The lines hang from pylons on ceramic insulators.
The table shows information about copper and aluminium.
| Metal | Relative electrical conductivity | Density / g cm−3\mathrm{g\,cm^{-3}}gcm−3 | Relative cost |
|---|---|---|---|
| copper | 100 | 8.96 | 3.0 |
| aluminium | 61 | 2.70 | 1.0 |
Explain why copper conducts electricity.
Give two properties of PVC that make it suitable for covering copper wires in homes.
Suggest why aluminium is used instead of copper for overhead power lines, even though it is a poorer conductor.
Suggest why the aluminium wires are wound around a steel core.
Give two properties of ceramics that make them suitable for the insulators on pylons.
36 exam-style questions on Edexcel GCSE Chemistry 10.5 Bulk and surface properties of matter including nanoparticles, covering 10.5.1 Nanoparticles: size, uses and risks and 10.5.2 Comparing and selecting materials. Each one has a worked solution and a mark scheme showing where the marks go.