$A$ metallic sphere has a charge of $10\,\mu C$. $A$ unit negative charge is brought from $A$ to $B$,both $100\,cm$ away from the sphere,with $A$ being east of it and $B$ being west of it. The net work done is........$joule$.

If a unit positive charge is taken from one point to another over an equipotential surface,then

$A$ circle of radius $R$ is drawn in a uniform electric field as shown in the figure. If the potentials at points $A, B, C,$ and $D$ on the circumference of the circle are $V_A, V_B, V_C,$ and $V_D$ respectively,then:

This question has Statement-$1$ and Statement-$2$. Of the four choices given after the Statements,choose the one that best describes the two Statements.
Statement-$1$: No work is required to be done to move a test charge between any two points on an equipotential surface.
Statement-$2$: Electric lines of force at the equipotential surfaces are mutually perpendicular to each other.

In an electric field due to charge $Q$,a charge $q$ moves from point $A$ to $B$ along an arc of a circle centered at $Q$,as shown in the figure. The work done is ($\varepsilon_0=$ permittivity of free space).

Define an equipotential surface.