\[ U\left( x \right) = Ex \] \[ U_m = E\left( {d - h} \right) \] \[ C = C_1 + C_2 = \frac{S}{{4\pi d_1 }} + \frac{S}{{4\pi d_2 }} = \frac{S}{{4\pi }}\left( {\frac{1}{{d_1 }} + \frac{1}{{d_2 }}} \right) \] \[ \frac{q}{U} = C \] \[ \left\{ {\begin{array}{*{20}c} {Q_A - Q_C = Q_B } \\ {Q_A + Q_C = Q + Q_B } \\ \end{array}} \right. \] \[ \begin{array}{*{20}c} {q = CU} \\ {Q = \frac{S}{{4\pi }}\left( {\frac{1}{{d_1 }} + \frac{1}{{d_2 }}} \right)U + Q_B } \\ \end{array} \] \[ Q_A = \frac{Q}{2} + Q_B \]

$ q_B = \frac{SU}{4\pi }\left( \frac{1}{d_1 } + \frac{1}{d_2 } \right),$

$ q_A = \frac{1}{2}\left( q - \frac{SU}{2\pi d_1 } \right),$

$q_C = \frac{1}{2}\left( q - \frac{SU}{2\pi d_2 } \right).$