Four point charges -q, +q, +q and -q are placed on y-axis at y = -2d, y = -d, y = +d and y = +2d, respectively. The magnitude of the electric field E at a point on the x-axis at x = D, with D >> d, will behave as:
1
\(E \propto \frac{1}{{{D^3}}}\)
2
\(E \propto \frac{1}{D}\)
3
\(E \propto \frac{1}{{{D^4}}}\)
4
\(E \propto \frac{1}{{{D^2}}}\)