To calculate how much copper can be produced by a one-meter-long, 20-square-millimeter conductor, assume that the cross-sectional area of the conductor is a square millimeter, the length is l meters, and the density of copper is ρ kg/m3. The weight of copper can be calculated by the following mathematical formula: the weight is equal to ρ times A times L, and the cross-sectional area of 20 square millimeters of wire is equal to 20 square millimeters.

The density ρ of copper is equal to 8.96kg/m3, and the length L of the wire is equal to 1m, so substituting these values into the above formula, it can be concluded that a wire with a length of 20m can produce 179.2kg of copper.