How to solve this prob. If can help please help.you will be very kind.

Dear Yogesh

let A,B,C are three vertices ...

charge at A,B is q but at C charge is -2q ...

A(q) ...................B(q)

C(-2q)

charge of C can be written as -q + -q

q charge of A & -q charge of C becomes 1 dipole ...

q charge of B & another -q charge of C makes another dipole ..

direction of dipole moments of  both is rowards C .....

angle bw them will be 60^o ...

now resultant = root(p²+p²+2p²cos60^o) = root3 (P)

now , P = qa so resultant = root3(qa)

Regards

Arun (askIITians forum experts)