# Electric Dipole-

 A system of two equal and opposite charges separated by a small distance is called as an electric dipole.

For example- two charges +q and -q separated by a small distance 2ℓ constitute an electric dipole.

Here,

• The distance (2ℓ) between the two charges is called as dipole length.
• The mid point of the line joining +q and -q charges is called as center of the electric dipole.

#### Charge On An Electric Dipole-

By additive nature of electric charge, we have-

 Total charge on an electric dipole = +q + (-q) = 0

However, the charge on an electric dipole is equal to the magnitude of either charge of the electric dipole.

For example- If charge on an electric dipole is 5 µC, then one charge is +5 µC and the other charge is -5 µC.

Also Read- Properties of Electric Charge

#### Examples of Electric Dipoles-

The examples of electric dipoles are-

• Molecules of water (H2O)
• Molecules of ammonia (NH3)
• Molecules of hydrochloric acid (HCl)
• Molecules of carbon dioxide (CO2)
• Molecules of sodium chloride (NaCl)
• Molecules of alcohol etc

## Electric Dipole Moment-

 Electric dipole moment of an electric dipole is defined as the product of the magnitude of either charge of the electric dipole and the dipole length.

It is a vector quantity having its direction from negative to positive charge. It is denoted by p.

#### Mathematically,

• The magnitude of electric dipole moment is p = q x 2ℓ.
• The direction of electric dipole moment is from negative to positive charge.
• The SI unit of electric dipole moment is coulomb meter (C m).
• The dimensional formula of electric dipole moment is [M0L1T1A1].