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Before we get into the differences between a magnetic dipole and magnetic intensity, we need to understand magnetism. The class of physical attributes mediated by a magnetic field referring to the capacity to induce attractive and repulsive phenomena in other entities is known as magnetism. 

It is one aspect of the combined phenomenon of electromagnetism. We can mostly observe it in ferromagnetic materials such as iron, cobalt, nickel, and their alloys. Magnetic fields can attract these materials and magnetise them to become permanent magnets that produce magnetic fields themselves; however, the demagnetisation of a magnet is also possible. 

The magnetic attraction decreases with distance though the exact mathematical relationship between the strength and distance varies.  

What is a Magnetic Dipole Moment?

The ability to turn itself into alignment with an external magnetic field is used to measure the strength of a magnetic dipole and is called a magnetic dipole moment. The magnitude of the magnetic dipole moment is proportional to the maximum amount of torque on the dipole in the case of a uniform magnetic field. 

Therefore, we can use the maximum torque caused by magnetic force on a dipole that arises per unit value of the surrounding magnetic field in a vacuum to define the magnetic dipole moment.  

The magnetic dipole moment formula is as below.

In the magnetic dipole moment formula above, 

  • m stands for magnetic
  • Br stands for Residual Flux Density
  • V stands for magnet volume
  • µ0 stands for magnetic permeability

There are two kinds of dipoles, an electric dipole and a magnetic dipole. 

Electric Dipole

A pair of equal and opposite electric charges whose centres aren’t coincident because the atom within which the centre of the negative cloud of electrons has been shifted off from the nucleus by an electrical field constitutes an induced electric doublet. 

A permanent electric dipole is called an electret, a dielectric material with a quasi-permanent electric charge or dipole polarisation. It generates internal and external electric fields and is the electrostatic equivalent of a permanent magnet. 

Magnetic Dipole

The limit of a closed-loop of electrical current or a pair of poles is known as a magnetic dipole. It is because the size of the source is reduced to zero while keeping the torsion constant. 

There has been a theoretical concept of the monopole, but scholars have not observed it in nature. 

Two models give the same predictions for a magnetic field far from the source for a dipole called the current loop and magnetic poles. So, any magnetic source looks like a dipole of the same magnetic moment at greater distances. 

Magnetic Intensity

We can define magnetic intensity as the degree to which a magnetic field magnetises a substance or the capability of an external magnetic field to magnetise the substance. 

Magnetic intensity is when we define a magnetic field as the number of magnetic lines of force passing normally per unit area about that point taken in free space without any substance. 

Therefore, the magnetic intensity is the number of ampere-turns flowing around a unit length of a toroidal solenoid to produce that magnetic field in it. 

The magnetic field strength is also called the magnetic field intensity. We can represent it by vector H, which is the ratio of the MMF needed to create a certain Flux Density (B) within a particular material and its per unit length. 

The formula for Magnetic Field Intensity is:

Where B is the magnetic flux density, M is the magnetisation, and µ is the magnetic permeability. 

Differences in Magnetic Intensity and Magnetic Dipole

To know the difference between magnetic intensity and magnetic dipole, we have to know the key characteristics and properties that differ from the other. 

The key characteristics of a magnetic dipole are as follows: 

  1. In the case of self-similarity of dipole field lines, they all make the same angle concerning the radial at a fixed latitude which means that the north-south component of every dipole field changes sign at the fixed latitude. 
  2. A dipole field strength is parallel to the radial direction over the poles and perpendicular to the radial direction in the equator, which means it is twice as strong at the pole as at the equator at a fixed radial distance; thus, the field strength is dependent on distance and latitude. 
  3. There is a scalar potential Ø and a vector potential A from which differentiation may generate field equations. The dipole field is curl-free due to no current and divergence-free, just like all magnetic fields. 

The key characteristics of magnetic intensity are as follows:

  1. Magnetic intensity is the ratio of the magnetising field strength to the permeability of free space. It describes the magnetic phenomenon’s quantity in terms of a magnetic field. 
  2. It is the portion of a material’s magnetic field generated by an external current instead of being intrinsic to the material itself. We measure it in amperes per metre. We can represent it as vector H, defined as H = B/µ – M. 
  3. Also called magnetic force, the magnetic intensity is the degree to which a magnetic field can magnetise a substance or the external magnetic field’s capability to magnetise the substance. 

Conclusion

Magnetism is present in nature, and all substances exhibit some magnetism, even to a low extent. It is ferromagnetism responsible for many of the effects of magnetism that we encounter in our day-to-day life. 

In the case of electromagnetism, the electrical current produces the magnetic field of an electromagnet. The magnetic field goes away when we turn off the electrical current. 

Therefore, when an electric current creates a magnet, it is easy to change the magnetic field by controlling the current of the electricity provided to the winding.