Step 1: Understanding the concept.
For two equal and opposite charges, the points of zero potential occur where the potentials due to both charges cancel out. These points are equidistant from both charges.
Step 2: Geometry of zero potential surface.
In three-dimensional space, the locus of points equidistant from both charges forms a cylindrical surface around the line joining them.
Step 3: Conclusion.
Thus, points having zero potential lie on a cylindrical surface.

At a particular temperature T, Planck's energy density of black body radiation in terms of frequency is \(\rho_T(\nu) = 8 \times 10^{-18} \text{ J/m}^3 \text{ Hz}^{-1}\) at \(\nu = 3 \times 10^{14}\) Hz. Then Planck's energy density \(\rho_T(\lambda)\) at the corresponding wavelength (\(\lambda\)) has the value \rule{1cm}{0.15mm} \(\times 10^2 \text{ J/m}^4\). (in integer)
[Speed of light \(c = 3 \times 10^8\) m/s]
(Note: The unit for \(\rho_T(\nu)\) in the original problem was given as J/m³, which is dimensionally incorrect for a spectral density. The correct unit J/(m³·Hz) or J·s/m³ is used here for the solution.)