The electric field due to an unknown charge distribútion is given by E = exp(-4r)F The total integrated charge over all space J pdV isgiveñ by (a) 0 [IISc. 2009] (b) q (cq/4 (d) q/7
I used this formula in this ques.. because divergence of r cap/r^2 =4π* dirac Delta... if you don't use this ,you will get wrong solution.. this is exceptional case..