Two identical positive charges are placed on the $y$-axis at $y=-a$ and $y=+a$. The variation of $V$ (electric potential) along the $x$-axis is shown by which graph?

Two conducting spheres of radii $9 \,cm$ and $1 \,cm$ are separated by a distance of $20 \,cm$ in free space. If the spheres are charged to the same potential of $10 \,V$ each, the force of repulsion between them is

An electron with an initial speed of $4.0 \times 10^6 \, m/s$ is brought to rest by an electric field. The mass and charge of an electron are $9 \times 10^{-31} \, kg$ and $1.6 \times 10^{-19} \, C$, respectively. Identify the correct statement.

There are two thin wire rings,each of radius $R$,whose axes coincide. The charges of the rings are $q$ and $-q$. The magnitude of potential difference between the centres of the rings separated by a distance $\sqrt{3} R$ is

$A$ charge of $8 \; mC$ is located at the origin. Calculate the work done in $J$ in taking a small charge of $-2 \times 10^{-9} \; C$ from a point $P (0, 0, 3 \; cm)$ to a point $Q (0, 4 \; cm, 0)$,via a point $R (0, 6 \; cm, 9 \; cm)$.

Calculate the electrostatic potential energy of a system of two charges $7\ \mu C$ and $-2\ \mu C$ placed at points $(-9\ cm, 0, 0)$ and $(9\ cm, 0, 0)$ respectively (in the absence of an external field).