In physics, there are several kinds of dipoles:
- An electric dipole is a separation of positive and negative charges. The simplest example of this is a pair of electric charges of equal magnitude but opposite sign, separated by some (usually small) distance. A permanent electric dipole is called an electret.
- A magnetic dipole is a closed circulation of electric current. A simple example of this is a single loop of wire with some constant current flowing through it.
- A flow dipole is a separation of a sink and a source. In a highly viscous medium, a two-beater kitchen mixer causes a dipole flow field.
- An acoustic dipole is the oscillating version of it. A simple example is adipole speaker.
- Any scalar or other field may have a dipole moment.
The Earth’s magnetic field, approximated as a magnetic dipole. However, the “N” and “S” (north and south) poles are labeled here geographically, which is the opposite of the convention for labeling the poles of a magnetic dipole moment