A spherical shell of radius ‘a’ with charge ‘Q’ is expanded to radius ‘2a’, work done by the electrical force in the process is

• A

  $\frac{{\mathrm{Q}}^2}{16{\mathrm{\pi e}}_{\mathrm{o}}\mathrm{a}}$

• B

  $\frac{{\mathrm{Q}}^2}{8{\mathrm{\pi e}}_{\mathrm{o}}\mathrm{a}}$

• C

  $\frac{{\mathrm{Q}}^2}{24{\mathrm{\pi e}}_{\mathrm{o}}\mathrm{a}}$

• D

  $\frac{3{\mathrm{Q}}^2}{4{\mathrm{\pi e}}_{\mathrm{o}}\mathrm{a}}$