A square loop of wire \(1.00 \mathrm{~m}\) on a side is at rest and has a linear charge density of zero in the Earth reference frame. The loop lies in the \(x y\) plane of an \(x y z\) coordinate system, and there is a clockwise electric current through the loop as seen by a person looking down the positive \(z\) axis to the \(x y\) plane. The electrons move at speed \(v\), and an observer \(\mathrm{M}\), moving at this same speed \(v\), approaches the loop along the \(y\) axis (moving in the positive \(y\) direction). In which side(s) of the loop ( \(+x,+y,-x,-y)\) does \(\mathrm{M}\) see the linear charge density as being due \((a)\) to surplus positive charge carriers and \((b)\) to surplus negative charge carriers?