Force calculation gives N instead of N/m

Hi,

I draw two beams next to each other in cross-section (a 2D simulation) and apply 1V to one and 0V to the other, and solve for electric field. When I do a Force Calculation in COMSOL v4.3a for beam #1 I get 1.3e-11 N. When I do a force calculation for beam#2 I get the same number in negative form as I'd expect by symmetry. When I do a force calculation for a box containing both beams I get something near zero, as I'd expect. See attached file.

However my problem is, I was expecting to get a force-per-meter [N/m, not N]. Because integrating the stress tensor for such a 2D simulation should give force-per-meter, and then when you go to do a 3D simulation you apply that force-per-meter at each point along the z-dimension of the beam.

What is going wrong?

Thanks,
David