Experiments with magnets and conductors
Density*resistivity of materials
|metal||density * resistivity|
Aluminum is by far the best, that's why it is used by the power companies for the high voltage power cables strung from tower to tower. It is very light and a very good conductor, and inexpensive, too! A great combination. Copper comes next, amazing since it is heavier than iron.
The units here are g/cm^3 * nano-ohm-meters.