Two short dipoles `phat(k)` and `P/2 hat(k)` are located at `(0,0,0)` & `(1m, 0,2m)` respectivley. The resultant electric field due to the two dipoles at the point `(1m, 0,0)` is

Options

A. `(9p)/(32 pi in_(0))`
B. `(-7 p)/(32 pi in_(0))`
C. `(7p)/(32 pi in_(0))`
D. none of these

Answer

B

Explanation

ltbtgt The at axis of `(P)/(2)` dipole and at equilitrial of P dipole so total field at given points is
`vec(E)=(kvec(P))/((1)^(3))+(2k(vec(P)//2))/((2)^(3))`
`=K.vec(P)(-1+(1)/(8))=(-7P)/(32 pi x_(0))`