The electric field strength at a distant point on the equatorial line of an electric dipole isDirectly proportional to distanceInversely proportional to distanceInversely proportional to the square of the distanceInversely proportional to the cube of the distance

The electric field strength at a distant point on the equatorial line of an electric dipole is inversely proportional to the cube of the distance.

Here's a step-by-step explanation:

1. An electric dipole consists of two equal and opposite charges separated by a small distance.

2. The electric field E at a point on the equatorial line of the dipole is given by the formula E = 1/4πε₀ * 2p/r³, where p is the dipole moment, r is the distance from the center of the dipole to the point, and ε₀ is the permittivity of free space.

3. From this formula, we can see that the electric field E is inversely proportional to the cube of the distance r. This means that as the distance r increases, the electric field E decreases, and vice versa.

4. Therefore, the electric field strength at a distant point on the equatorial line of an electric dipole is inversely proportional to the cube of the distance.