When choosing between copper and aluminum wire, which factor explains why aluminum is often used?

When choosing between copper and aluminum wire, which factor explains why aluminum is often used?

• A. Copper conducts better with lower resistance, so it is preferred in all cases.
• B. Aluminum is heavier than copper, which is why it is rarely used.
• C. Copper is cheaper than aluminum, so aluminum is never chosen.
• D. Aluminum is lighter than copper, and for this reason, as well as cost considerations, aluminum is often used when the weight factor is important.

Answer: (D)

The main idea here is balancing electrical performance with weight and cost. Aluminum is much lighter than copper—about a third of copper’s density—so for long wiring runs, using aluminum can substantially reduce aircraft weight. Although aluminum has higher resistivity and may require a larger cross-section to carry the same current, the weight savings often outweigh the extra material needed. Add in generally lower cost per pound, and aluminum becomes a favorable choice when weight is a critical factor.

The main idea here is balancing electrical performance with weight and cost. Aluminum is much lighter than copper—about a third of copper’s density—so for long wiring runs, using aluminum can substantially reduce aircraft weight. Although aluminum has higher resistivity and may require a larger cross-section to carry the same current, the weight savings often outweigh the extra material needed. Add in generally lower cost per pound, and aluminum becomes a favorable choice when weight is a critical factor.