A very large sphere having charge 100e (e is equal to the charge of electron) uniformly distributed on the surface is compressed slowly and uniformly till its radius reduces to 1 m. The work done by the electric forces in this process is: (in J)

• A

  ${10}^{13}\times e^2$

• B

  $4.5\times {10}^9\times e^2$

• C

  $9\times {10}^{13}\times e^2$

• D

  $4.5\times {10}^{13}\times e^2$