Find the magnitude of the electric field intensity with a copper sample if: (a) the current density is 106 A/m²; (b) the free-electron velocity is 0.1 mm/s; (c) it is in the form of a cube, 1 mm on a side, carrying a total current of 2 A; (d) it is in the form of a cube, Í mm on a side, with a potential difference of 20 uV between opposite faces.

Find the magnitude of the electric field intensity with a copper sample if: (a) the current density is 106 A/m²; (b) the free-electron velocity is 0.1 mm/s; (c) it is in the form of a cube, 1 mm on a side, carrying a total current of 2 A; (d) it is in the form of a cube, Í mm on a side, with a potential difference of 20 uV between opposite faces.