A pair of long, rigid metal rods, each of length L, lie parallel to each other on  a perfe...

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 conducting springs of force constant k (Figure) and negligible unstreched 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.

Figure: