दिए गए आवेशों के निकाय की कुल स्थिरवैद्युत ऊर्जा को गणना कीजिए।

Answer

`(-sqrt2q^(2))/(4piepsi_(0)a)`

Explanation

`U=(1)/(4piepsi_(0)) [(q_(A)q_(B))/(AB)+(q_(A)q_(C))/(AC)+(q_(A)q_(D))/(AD)+(q_(B)q_(C))/(BC)+(q_(B)q_(D))/(BD)+(q_(C)q_(D))/(CD)]`
`=9 xx 10^(9)[(q(-q))/(a)+(q(-q))/(sqrt2a)+(q.q)/a+(-q(-q))/(a)+(-q(q))/(sqrt2a)+(-q.q)/(a))]`
`=-9 xx 10^(9) (sqrt2q^(2))/(a)=(1)/(4piepsi_(0)).(-sqrt2q^(2))/(a)`