If a charge $+Q$ is placed at each corner of a cube,what is the electric field at the center of the cube? $\left( k = \frac{1}{4\pi\varepsilon_0} \right)$

The dimensional formula of electric field is . . . . . . .

Six point charges are placed at the vertices of a regular hexagon of side $a$ as shown in the figure. Three charges are $+Q$ and three are $-Q$ arranged alternately. The electric field intensity at a point on the line passing through the centre $O$ and perpendicular to the plane of the figure at a large distance $x (x \gg a)$ from $O$ is (Let $\frac{1}{4 \pi \epsilon_0} = k$):

As shown in the figure,at what distance in $cm$ from point $A$ will the electric field be zero?

$A$ uniformly charged sphere has a total charge $Q$ and radius $R$. The electric field $E$ is a function of the distance $r$ from the center. Which of the following graphs represents this relationship?

Electric field in a certain region is given by $\overrightarrow{E} = (\frac{A}{x^2} \hat{i} + \frac{B}{y^3} \hat{j})$. The $SI$ units of $A$ and $B$ are: