Equipotential surfaces associated with an electric field which is increasing in magnitude along the $x$-direction are

Equipotential surfaces at a very large distance from a collection of charges whose total sum is not zero are approximately . . . . . . .

The figure shows equipotential surfaces concentric at $O$. The magnitude of the electric field at a distance $r$ metres from $O$ is

Three infinitely long wires with linear charge density $\lambda$ are placed along the $x$-axis,$y$-axis,and $z$-axis respectively. Which of the following denotes an equipotential surface?

As shown in the figure below,a charge $+2 \text{ C}$ is situated at the origin $O$ and another charge $+5 \text{ C}$ is on the $x$-axis at point $A(2, 0) \text{ m}$. The charge at point $A$ is then moved to point $B(0, 2) \text{ m}$ on the $y$-axis. Calculate the work done. (Given $\frac{1}{4 \pi \varepsilon_{0}} = 9 \times 10^{9} \text{ N m}^2/\text{C}^2$)

What is the direction of the lines of force at any point on the equipotential surface?