In the rectangle, shown below, the two corners have charges $q_1=-5 \mathrm{\mu C}$ and $q_2=+2.0 \mathrm{\mu C}$. The work done in moving a charge $+3.0 \mathrm{\mu C}$ from $B$ to $A$ is (take $1/4\mathrm{\pi }{\epsilon }_0={10}^{10} {\mathrm{Nm}}^2 {\mathrm{C}}^{-2}$ )

         

A point charge is surrounded symmetrically by six identical charges at distance $r$ as shown in the figure. How much work is done by the forces of electrostatic repulsion when the point charge $q$ at the centre is removed at infinity?

An electric field $E$ whose direction radially outward varies as distance from the origin $r$ as shown in the graph. $E$ is taken as positive if its direction is away from the origin. Then the work done by the electric field on a $2 \mathrm{C}$ charge if it is taken from $\left(1, 1, 0\right)$ to $\left(3, 0, 0\right)$ is

A uniform surface charge of density $\sigma$ is given to a quarter of a disc extending up to infinity in the first quadrant of $x-y$ plane. The centre of the disc is at the origin $O$. Find the $z$-component of the electric field at the point $\left(0,0,z\right)$ and the potential difference between the points $\left(0,0,d\right)$ and $\left(0,0,2d\right)$.

Electric potential is given by $V=6x-8x{y}^2-8y+6yz-4z^2$. The electric force acting on $2 \mathrm{C}$ point charge placed on origin will be?