In the electric field of a point charge $q$,a certain charge is carried from point $A$ to points $B, C, D$ and $E$ as shown in the figure. Then the work done:

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?

What is the angle between an equipotential surface and electric lines of force (in $^{\circ}$)?

The figure shows lines of constant potential in a region where an electric field is present. The electric field at point $B$ is............

$A$ circle of radius $R$ is drawn with a charge $+q$ at the centre. $A$ charge $q_0$ is moved from point $B$ to $C$ along the circumference of the circle. The work done is:

Two point charges $-Q$ and $+Q / \sqrt{3}$ are placed in the $xy$-plane at the origin $(0,0)$ and a point $(2,0)$,respectively,as shown in the figure. This results in an equipotential circle of radius $R$ and potential $V = 0$ in the $xy$-plane with its center at $(b, 0)$. All lengths are measured in meters.
$(1)$ The value of $R$ is. . . . meter.
$(2)$ The value of $b$ is. . . . . .meter.