A point electric dipole \(\vec{P}=p_x \hat{\imath}\) is placed at a vertical distance d above a grounded infinite conducting xy plane as shown in the figure.
At a point \(\vec{r} \quad(r \gg d, z>0)\) far away from the dipole, the electrostatic potential V(r) varies approximately as
1
\(\frac{1}{r^2}\)
2
\(\frac{1}{r^6}\)
3
\(\frac{1}{r^3}\)
4
\(\frac{1}{r^4}\)