A pair of long, rigid metal rods, each of length L, lies parallel to each other on a perfectly smooth table. Their ends are connected by identical, very light conducting springs of force constant k (Fig) and negligible unstretched length. If a current I runs through this circuit, the springs will stretch. At what separation will the rods remain at rest? Assume that k is large enough so that the separation of the rods will be much less than L.