High voltage power transmission lines are made out of aluminum with a crosssectional area of about 4.4 x 10-4m^2. These lines typically carry currents of 1.3-A.
The transmission current and the return current flow through high tension cables strung roughly 0.5-m apart. Prove that we should not notice the forces exerted on the wires by the Earth's magnetic field (average strength of 0.50 Gauss) on on each other.
Compare the forces per unit length with their weight per unit length.