# Dipole & Dipole Moment – definition, formula

Last updated on March 24th, 2022 at 04:06 pm

In this post, we will find out what exactly an electric **dipole** is. We will also define **dipole moment** and find out the formula of dipole moment.

## Dipole | Electric Dipole

If two equal and opposite charges are separated by a small distance, the system is said to form a dipole. The most familiar example is H_{2}O.

Figure 1 shows charges +q and – q separated by a small distance 2l.

## Dipole Moment

The product of the magnitude of charge and separation between the charges in a dipole is called dipole moment, p.

To get the magnitude of the charge of a dipole take the magnitude of any member charge, as magnitude wise both charges are the same.

The equation of the dipole moment p is as follows: **p = q × 2l** ………………. (1)

Its SI unit is coulomb-metre.

The dipole moment is a **vector** quantity. Equation (1) gives its magnitude and its direction is from negative charge to positive charge along the line joining the two charges (axis of the dipole).

**The magnitude of the dipole moment**: **p = q × 2l**

**The direction of the dipole moment:** from negative charge to positive charge along the line joining the two charges (axis of the dipole)

The **net charge on an electric dipole is zero**.

Having defined a dipole and dipole moment, we are now in a position to calculate the electric field due to a dipole. Read this post: **electric field due to a dipole on its axis and on its equatorial line – with formulas**

Also read: **Torque on an electric dipole**