Key Factors
Electrical Conductivity:
Pure copper has a higher intrinsic conductivity (58.0 MS/m) than aluminum (37.7 MS/m). This means copper conducts electricity better per unit volume.
Density:
Copper is much denser (~8.96 g/cm³) than aluminum (~2.70 g/cm³). Aluminum is ~69% lighter for the same volume.
Volume vs. Weight
By Volume:
Copper's higher conductivity means it carries more current per cubic centimeter. For example, a copper wire of the same thickness as an aluminum wire will have lower resistance.
By Weight:
Aluminum's lower density allows you to use more material (larger cross-sectional area) for the same weight. This compensates for its lower conductivity:
A 1 kg aluminum wire can be made thicker/longer than a 1 kg copper wire.
The larger aluminum wire reduces resistance, making it more conductive per kilogram.
Practical Example
Power Lines:
Aluminum is preferred for overhead cables because:
A thicker aluminum cable (same weight as copper) has comparable resistance but is lighter, cheaper, and easier to install.
Example: An aluminum cable with 50% larger cross-section than copper will weigh ~50% less and conduct similarly.
Copper's Edge:
Copper is used where space/volume matters (e.g., household wiring, electronics) because it packs more conductivity into a compact form.
