$A$ uniform electric field of magnitude $100 \ V/m$ in space is directed along the line $y = 3 + x$. Find the potential difference between point $A(3, 1)$ and $B(1, 3)$ in Volts.

$A$ charge $+Q$ is placed at the centre of a circular path of radius $r$. The work done to bring a charge $+q$ from one end of the diameter to the other end of the circular path in the electric field produced by charge $+Q$ is $.......$

At which point is the electric field maximum?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: Work done by an electric field on moving a positive charge on an equipotential surface is always zero.
Reason $(R)$: Electric lines of force are always perpendicular to equipotential surfaces.
In the light of the above statements,choose the most appropriate answer from the options given below:

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:

$A$ uniform electric field exists in the plane of the paper as shown. Here $A, B, C$, and $D$ are points on the circle. $V_{A}, V_{B}, V_{C}$, and $V_{D}$ are the potentials at those points respectively. Then: