The electric field lines on the left have twice the separation of those on the right as shown in the figure. If the magnitude of the electric field at $A$ is $40 \ Vm^{-1}$,what is the force on a $20 \ \mu C$ charge kept at $B$?

Find out the electric field intensity at point $A(1, 0, 2)$ due to a point charge $-20\,\mu C$ situated at point $B(0, 2, 1)$.

Two point charges $-q$ and $+q/2$ are situated at the origin $(0, 0, 0)$ and at the point $(a, 0, 0)$ respectively. The point along the $X$-axis where the electric field vanishes is:

$A$ conducting sphere of radius $10 \, cm$ has an unknown charge. If the electric field at a distance $20 \, cm$ from the centre of the sphere is $1.2 \times 10^3 \, N \, C^{-1}$ and points radially inwards,the net charge on the sphere is:

In the given figure,the electric field at the center $O$ due to section $AB$ of a uniformly charged ring is $\overrightarrow{E}$. What will be the electric field at $O$ due to the remaining section $ACB$?

$A$ wire of length $L = 20 \, cm$ is bent into a semicircular arc. If the two equal halves of the arc are uniformly charged with charges $+Q$ and $-Q$ respectively,where $|Q| = 10^3 \varepsilon_0$ Coulomb and $\varepsilon_0$ is the permittivity of free space,find the net electric field at the centre $O$ of the semicircular arc.