Two parallel, infinitely straight lines currents, I1 and I2, (but opposite in direction) are separated by a distance d. Find the magnitude of the force per length between them (“force per length” so that it wouldn’t be an infinite force between them). Indicate whether the force would be attractive or repulsive.

Two parallel, infinitely straight lines currents, I1 and I2, (but opposite in direction) are separated by a distance d. Find the magnitude of the force per length between them (“force per length” so that it wouldn’t be an infinite force between them). Indicate whether the force would be attractive or repulsive.