There is a system of 4 infinite length uniformly charged wire passing through corners of a rectangle ABCD and perpendicular to the plane of rectangle as shown in figure. Charge density of wires passing through A, D is $\lambda$ and B and C is  $2\lambda$.  $P_1,P_2,P_3$ and $P_4$ are points on the perpendicular bisector of AD and BC. (q is positive charge)

Potential energy of system is increasing continuously if a charge particle ‘q’ is moved from $P_1$ to O along perpendicular bisectors

Potential energy of system first increases and then decreases if charge is moved from  $P_2$ to O along perpendicular bisector line.

Potential energy of system 1st increase then decrease if a charge particle ‘q’ is moved from O to $P_3$

Potential energy of system decrease continuously if a charge particle ‘q’ is moved from $P_2$ to O along perpendicular bisector line