A pair of long, rigid metal rods each of length L, lie parallel to each other on a perfectly smooth table. Their ends are connected by identical, very light conduction springs of force constant k each and negligible unstretched length. If the current I runs through the 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 rods will be much less than L. Express your answer in terms of I, L, k and appropriate constants (μo,π).