Question

An electric dipole of moment vector p = (-i - 3j + 2k) x 10^-29 C. m is at the origin (0, 0, 0). The electric field due to this dipole at vector r = i + 3j + 5k (note that vector(r.p) = 0) is parallel to: 

Answer 1

Answer is (3) (i + 3j - 2k)

Answer 2

Answer is (3) (i + 3j - 2k)

Since vector(r and p) are perpendicular to each other therefore point lies on the equitorial plane. Therefore electric field at the point will be antiparallel to the dipole moment. i.e. 

vector E || - vector p

vector E || (i + 3j - 2k)