The two wires, each having a weight per unit length 10^-4 N/m, are parallel, with one directly above the other. Suppose that the wires carry currents which are equivalent in magnitude and opposite in direction. The wires are 0.1 m apart and the sum of the magnetic force and gravitational force on the upper wire is zero. Determine the magnitude of the current in the wires. (Avoid the magnetic field of Earth)