The sketch below shows cross-sections of the equipotential surface between two charged conductors that are shown in solid black. Some points on the equipotential surfaces near the conductors are marked as $\mathrm{A}$, $\mathrm{B}$, $\mathrm{C}$.......... The arrangement lies in the air. $\left(\mathrm{Take}\mathrm{ }{\mathrm{ϵ}}_0=8.85\times {10}^{-12}\mathrm{ }{\mathrm{C}}^2 {\mathrm{N}}^{-1}\mathrm{ }{\mathrm{m}}^{-2}\right)$
The surface charge density of the plate is equal to