$E = kQ\left[ {\frac{1}{{{1^2}}} + \frac{1}{{{2^2}}} + \frac{1}{{{4^2}}} + \frac{1}{{{8^2}}} + …\infty } \right]$

$E = kQ\left[ {1 + \frac{1}{4} + \frac{1}{{16}} + \frac{1}{{64}} + …\infty } \right]$$1 + \frac{1}{4} + \frac{1}{{16}} + \frac{1}{{64}} + …\infty $

${S_\infty } = \frac{a}{{1 – r}}$ $a = 1$ , $r = \frac{1}{4}$ $1 + \frac{1}{4} + \frac{1}{{16}} + \frac{1}{{64}} + …..\,\infty = \frac{1}{{1 – 1/4}} = \frac{4}{3}$

$E = 9 \times {10^9} \times Q \times \frac{4}{3} = 12 \times {10^9}\,Q\,N/C$

$V = \frac{1}{{4\pi {\varepsilon _0}}}\left[ {\frac{{1 \times {{10}^{ – 6}}}}{1} + \frac{{1 \times {{10}^{ – 6}}}}{2} + \frac{{1 \times {{10}^{ – 6}}}}{4} + \frac{{1 \times {{10}^{ – 6}}}}{8} + …….\infty } \right]$

$ = \,9 \times {10^9} \times {10^{ – 6}}\left[ {1 + \frac{1}{2} + \frac{1}{4} + \frac{1}{8} + …………\infty } \right] = 9 \times {10^3}\left[ {\frac{1}{{1 – \frac{1}{2}}}} \right]$

$ = 1.8 \times {10^4}\,volt$