
$\left(\mathrm{V}_{\mathrm{A}}-\mathrm{V}_{\mathrm{B}}\right)+15-8=\frac{13}{12 \times 10^{-6}} \mathrm{q}$
$19+15-8=\frac{13}{12 \times 10^{-6}} \mathrm{q}$
$\mathrm{q}=24 \,\mu \mathrm{c}$
${{\rm{V}}_{3\mu F}} = \frac{{24 \times {{10}^{ - 6}}}}{{3 \times {{10}^{ - 6}}}} = 8\,{\rm{volt}}$

Statement$ -1$ : When a charge $q$ is take from the centre of the surface of the sphere its potential energy changes by $\frac{{q\rho }}{{3{\varepsilon _0}}}$
Statement$ -2$ : The electric field at a distance $r(r < R)$ from centre of the sphere is $\frac{{\rho r}}{{3{\varepsilon _0}}}$
