Consider two long straight parallel wires each carrying a current I. If the currents move in the same direction?

The magnetic fields produced by the two wires will reinforce each other, creating a stronger magnetic field between them. This results in an attractive force between the wires. The force is given by the formula F = (μ0 * I1 * I2 * L) / (2πd), where μ0 is the permeability of free space, I1 and I2 are the currents, L is the length of the wires, and d is the distance between the wires.