Describe the uses of metals in terms of their physical properties, including: (a) aluminium in the manufacture of aircraft because of its low density (b) aluminium in the manufacture of overhead electrical cables because of its low density and good e

Metals – Uses of Metals

Metals are everywhere because they have special physical properties that make them useful for many everyday tasks. Below we look at two common metals – aluminium and copper – and see how their properties match the needs of different industries. 🚀⚡️🥫🔌

Aluminium (Al)

Aluminium is a lightweight, shiny metal that is very resistant to rust. Its low density (\$\rho{\text{Al}} \approx 2.7 \text{ g/cm}^3\$) and good electrical conductivity (\$\sigma{\text{Al}} \approx 3.5 \times 10^7 \text{ S/m}\$) make it perfect for many applications. Think of aluminium as a “super‑light” version of steel that can still carry heavy loads without getting heavy itself.

  1. Aircraft manufacturing – ✈️ Because aluminium is so light, planes can fly farther and use less fuel. Imagine a giant paper airplane that can still hold a lot of weight – that’s what aluminium does for real aircraft.

  2. Overhead electrical cables – ⚡️ Aluminium’s low weight and good conductivity mean that power lines can be thinner and lighter, reducing the amount of material needed and making them easier to install.

  3. Food containers – 🥫 Aluminium resists corrosion, so it won’t rust or leach into food. It keeps your snacks fresh and safe.

  4. Construction and architecture – 🏗️ Its strength and lightness also make it popular for building frames, window frames, and decorative elements.

Copper (Cu)

Copper is famous for being an excellent conductor of electricity and for its ability to be drawn into very thin wires without breaking. These traits make it the go‑to metal for electrical wiring. Think of copper as the “golden thread” that keeps our lights, phones, and computers running.

  • Electrical wiring – 🔌 Copper’s high conductivity (\$\sigma_{\text{Cu}} \approx 5.8 \times 10^7 \text{ S/m}\$) and ductility mean that wires can be made thin, flexible, and safe for carrying large currents.

Physical Properties Table

PropertyAluminiumCopper
Density\$2.7 \text{ g/cm}^3\$\$8.96 \text{ g/cm}^3\$
Electrical Conductivity\$3.5 \times 10^7 \text{ S/m}\$\$5.8 \times 10^7 \text{ S/m}\$
Corrosion ResistanceHigh – forms a protective oxide layerModerate – can oxidise to a reddish patina
DuctilityGood – can be drawn into wiresExcellent – can be drawn into very thin wires

Exam Tip: Remember that low density is key for aircraft and overhead cables, while high conductivity and ductility are essential for electrical wiring. Use the table to quickly match a property to its application when answering multiple‑choice questions. Good luck! 🍀