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

The nature of the equipotential surface for a point charge is:

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 $\frac{1}{4 \pi \varepsilon_{0}} = 9 \times 10^{9} \text{ N m}^2/\text{C}^2$)

$A$ conducting sphere of radius $r$ has a charge. Then

There are two equipotential surfaces as shown in the figure. The distance between them is $r$. If a charge of $-q \text{ C}$ is moved from surface $A$ to surface $B$,the resultant work done will be:

Electric field is always ...... to the equipotential surface at every point. (Fill in the gap)