Question

The electric field intensity $\vec{E}$, due to an electric dipole of moment $\vec{p}$, at a point on the equatorial line is

• A. parallel to the axis of the dipole and opposite to the direction of the dipole momen $\vec{p}$
• B. perpendicular to the axis of the dipole and is directed away from it
• C. parallel to the dipole moment
• D. perpendicular to the axis of the dipole and is directed toward it

Answer 1

Answer: (A)

Consider an electric dipole consisting of two point charges $-q$ and $+q$ separated by a small distance $AB=2a$ with centre at $O$,
As shown in figure, on equatorial line, the resultant electric field $\vec{E}$ of ${\vec{E}}_1$ and ${\vec{E}}_2$ is parallel to the axis of the dipole but opposite

to the direction of the dipole moment $\vec{p}$ as it is directed from negative charge to positive charge.