An electric dipole is placed as shown in the figure. The electric potential (in $10^2 \ V$) at point $P$ due to the dipole is ($\epsilon_0 =$ permittivity of free space and $\frac{1}{4 \pi \epsilon_0} = K$):

Two point charges $-20 \,\mu C$ and $+40 \,\mu C$ are separated by a distance $r$. At which region$(s)$ will the electric potential be zero?

Three point charges $+Q$,$+2Q$,and $q$ are placed at the vertices of an equilateral triangle. The value of charge $q$ in terms of $Q$,so that the electrical potential energy of the system is zero,is given by:

Given below are two statements $:$ one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A :$ Work done in moving a test charge between two points inside a uniformly charged spherical shell is zero,no matter which path is chosen.
Reason $R :$ Electrostatic potential inside a uniformly charged spherical shell is constant and is same as that on the surface of the shell.
In the light of the above statements,choose the correct answer from the options given below.

Derive an expression for the electric potential at a distance $r$ from a positive point charge $Q$.

$1 \ eV = ...... \ J$. (Fill in the gap)