$x + y =\frac{ d }{4}$
$\frac{ A \epsilon_{0}}{ d }= C _{0}$
$\Delta V = Ex +\frac{ E }{ k } \times \frac{3 d }{4}+ Ey$
$=\frac{3 Ed }{4 k }+ E ( x + y )$
$\Delta V = E \left[\frac{3 d }{4 k }+\frac{ d }{4}\right]$
$\Delta V =\frac{\sigma}{\epsilon_{0}}\left[\frac{3 d + dk }{4 k }\right]=\frac{ Qd }{ A \epsilon_{0}}\left[\frac{3+ k }{4 k }\right]$
$\frac{ Q }{\Delta V }= C =\frac{ A \epsilon_{0}}{ d }\left[\frac{4 k }{3+ k }\right]=\frac{4 k C _{0}}{ k +3}$

$STATEMENT-2$ The electrical potential of a sphere of radius $R$ with charge $\mathrm{Q}$ uniformly distributed on the surface is given by $\frac{\mathrm{Q}}{4 \pi \varepsilon_0 R}$.


