Uses of Metals

(a) Aluminium in the manufacture of aircraft

• Aluminium has a low density, which means it is lightweight. This reduces the overall weight of the aircraft, allowing it to fly more efficiently and use less fuel.
• Despite being light, aluminium is strong when alloyed with other metals such as copper and magnesium. This gives the strength needed to withstand air pressure and mechanical stress during flight.
• Aluminium also has good resistance to corrosion because it forms a thin, protective oxide layer. This is important for aircraft as they are exposed to varying weather conditions and moisture.

(b) Aluminium in the manufacture of overhead electrical cables

• Aluminium is a good conductor of electricity, though not as good as copper. Its conductivity is sufficient for long-distance transmission of electricity.
• Its low density makes aluminium cables much lighter than copper cables, which is very important for overhead transmission lines that must stretch over long distances between pylons.
• Aluminium also has good resistance to corrosion, making it suitable for outdoor use where cables are exposed to air and rain.
• Often, aluminium is used in cables with a steel core. The steel provides strength, while aluminium provides conductivity and lightness.

(c) Aluminium in food containers

• Aluminium forms a thin oxide coating on its surface, which protects it from further corrosion. This prevents food contamination and increases the durability of the container.
• It is non-toxic, so it does not react with food or affect its taste, making it safe for packaging.
• Aluminium is lightweight and malleable, so it can be easily pressed or rolled into thin sheets for cans and foils, making packaging cost-effective and easy to transport.
• It also reflects light and heat, helping to preserve food and drinks.

(d) Copper in electrical wiring

• Copper is one of the best electrical conductors due to the presence of many delocalised electrons, which can move freely to carry current.
• Copper is ductile, meaning it can be drawn into very thin wires without breaking. This is essential for making long electrical cables.
• Copper is also malleable, so it can be bent and shaped easily without cracking, which helps in installation of wiring in buildings and devices.
• It is tough and durable and does not corrode easily in dry air, ensuring long-term reliability in electrical systems.
• Its relatively high melting point means that wires will not melt under normal current flow, preventing fire hazards.