A long cylindrical shell carries positive surface charge $\sigma$ in the upper half and negative surface charge $–\sigma$ in the lower half. The electric field lines around the cylinder will look like figure given in:

(figures are schematic and not drawn to scale)

Figure shows three arrangements of electric field lines. In each arrangement, a proton is released from rest at point A and then accelerated through point B by the electric field. Points A and B have equal separations in the three arrangements. If $p_1,p_2$ and $p_3$ are linear momentum of the proton at point B in the three arrangement respectively, then

A charge $Q_1$ exerts some force on a second charge $Q_2.$ If a third charge $Q_3$ is brought near, the force of $Q_1$ exerted on $Q_2$: