# CBSE Class 12-science Answered

**Define Electric dipole. Derive an expression for electric feild intensity at a point situated at a distance r from electric dipole**

Two system charges, equal and opposite, are separated by a finite distance is called an electric dipole.

An equatorial line of a dipole is the line on a plane perpendicular to the dipole axis through its centre.

Consider a dipole consisting of -q and +q separated by a distance 2a. Let P be a point on the

equatorial line, as shown in figure.

The magnitude of the electric field due to the two charges +q and –q are given by

The resultant electric field is the vector sum of the intensity due to charge +q and –q.

EA and EB can be resolved into vertical and horizontal component.

The components along dipole axis add up to give resultant field.

The vertical components of EA and EB cancel each other because they are equal and oppositely

directed. Therefore,