Which of the following correctly represents the variation of electric potential $(V)$ of a charged spherical conductor of radius $(R)$ with radial distance $(r)$ from the centre?

The figure shows a solid hemisphere with a charge of $5 \ nC$ distributed uniformly throughout its volume. The hemisphere lies on a plane and point $P$ is located on this plane,along a radial line from the center of curvature at a distance of $15 \ cm$. The electric potential at point $P$ due to the hemisphere is ..... $V$.

As shown in the figure,charges $+q, +q, -q$ and $-q$ are placed on the vertices of a square,each side length is $2l$. The electric potential at the mid-point '$A$' of the charges $+q$ and $+q$ is . . . . . . .

Two concentric conducting spherical shells of radii $30 \, cm$ and $5 \, cm$ are charged. If the outer shell has a charge of $3 \, \mu C$ and the inner shell has a charge of $0.5 \, \mu C$,what is the electric potential on the outer spherical shell?

Two electric charges $12\,\mu C$ and $-6\,\mu C$ are placed $20\, cm$ apart in air. There will be a point $P$ on the line joining these charges and outside the region between them,at which the electric potential is zero. The distance of $P$ from the $-6\,\mu C$ charge is.......$m$.

The electric potentials at two points $P$ and $Q$ are $10 \ V$ and $-4 \ V$ respectively. The work done in moving $100$ electrons from $P$ to $Q$ is: