Magnetic Field Vs Magnetic Field Strength: Different Aspects and Facts

In this article, we are going to see the difference between the magnetic field and the magnetic field strength, some features, and facts.

A magnetic field is set up due to the motion of the charged particles and the captivation force is exerted in this region; magnetic field strength only intensifies this impact by increasing the magnetic flux density per unit length.

Magnetic Field Vs Magnetic Field Strength

Magnetic FieldMagnetic Field Strength
The field produced around the magnetic material due to the motion of the charged particle is known as a magnetic field.Force experienced per unit length of a conductor for the magnetic flux to penetrate through the conductor is called magnetic field strength.
The magnetic field is stable around the magnet.Magnetic field strength varies with distance.
Magnetic field depends on the velocity of the particle, external field, and the charge of the particle.Magnetic field strength depends upon the magnetic flux, dipole moment, magnetic susceptibility, permeability, magnetization, and the number of charged particles.
The magnetic field is a vector quantity that has both magnitude and directionMagnetic field strength is a scalar quantity that has only the magnitude and no direction
SI unit of the magnetic field is TeslaSI unit of magnetic field strength is Amperes per meter
CGS unit of the magnetic field is GaussCGS unit of magnetic field strength is Oersted

Let us closely understand the concept of the magnetic field and the intensity of the magnetic field.

In presence of the electric field, the charged particles are in a mobile state which produces a magnetic field. In the magnetic field region, the force perpendicular to the speed of the particle is emanated. In contrast, the magnetic field strength is a pressure experienced in that area relying upon the magnetic flux passing via a unit length of the material.

The magnetic field can be interpreted as field lines whereas magnetic field strength is a density of field lines crossing per unit cross-sectional area.

Let us don’t forget an easy instance of a bar magnet positioned in a tray of iron foils. We see that the iron foils are impeccably aligned around the bar magnet forming the closed loops.

Magnetic Field Vs Magnetic Field Strength
Traces of the alignment of iron foils around the bar magnet,
Image credits: comnewsscience

The concentric loops encircling the bar magnet move from the North Pole to the South Pole of the bar magnet, that means one pole is attractive and the alternative is repulsive. But, the direction of the flux flowing inside the bar magnet is aligned in the opposite direction. The magnetic field lines form the closed loops and never intersects. However, if overlapped, the path of the magnetic field isn’t unique.

The region surrounding a bar magnet in which this magnetic effect is observed is a magnetic field region. You will notice that more number of iron foils are attracted toward the magnet in the area circumjacent it, while the density of the field lines decreases as a gap between the magnet and a point of consideration increases. That is the strength of the magnetic field diminishes as we go away from the magnet, however, the magnetic field is stable.

Magnetic Moment and the Direction of a Magnetic Field

When the material having magnetic susceptibility greater than zero is placed in the electric field, the magnetic dipoles try to align themselves in the direction of the field. Due to the motion of dipoles, the magnetic field is installed in the material. The spin and orbital angular instigation of the electron and protons will decide the direction of the magnetic field.

During this alignment, there is a change in the concentration of positive and negative charge carriers per unit volume of the material. The charged carriers are aligned in the direction of the field forming the colonies. The more the number of the charged debris aligned in accordance with the magnetic field strength adds to the magnetization of the material.

The strength of the magnetic field is the force required for the magnetic flux to penetrate through the cross-sectional area of the material making it more magnetized. Hence the magnetic field strength primarily depends upon the magnetic field produced due to the motion of charged debris and the electric field implemented to the conductor and the magnetic flux density.

Read more on What Produces the Strength of the Magnetic Field.

Magnetic field and Intensity in free space and solid state

In free space, the magnetic field is linearly dependent on the intensity of the field, given by the relation:


where B is the magnetic field,

m is a permeability of free space and

H is a magnetic field strength.

The material is said to be more permeable if more number of magnetic fluxes are penetrating through the material. In the magnetic solid, the same is given by the product of permeability and the sum of the intensity of the field and magnetization of the material.



Where is a susceptibility.

The total magnetic moment induced per unit volume of a material is known as susceptibility and is inversely proportional to the strength of the magnetic field.

Motion of a Particle in a Magnetic Field

For a charged particle in an electric field, experiences both electric and magnetic forces, which is known an electromagnetic effect. It is formulated as:

Since the motion of the particle is perpendicular to the direction of the magnetic field applied, the force due to the magnetic field acts as a centripetal force on the particle as the force always acts towards the centre and produces circular motion perpendicular to the field.

In a uniform magnetic field, this circular motion remains unaffected thereby moving in a helical motion.



The above solution indicates that the magnetic field is directly proportional to the momentum of the particle and inversely proportional to its charge and a radius of a helix.

Scalar and Vector Quantities

The magnetic field is a vector quantity that has both magnitude and direction while the magnetic field strength is a scalar quantity that has only the magnitude and no direction.

The sum of the resultant forces experienced by the particles in the presence of a magnetic field conclusive the strength of the magnetic field. The magnitude of the field is derived by the number of flux lines passing through per unit area.

Unit of Magnetic field and Magnetic Field Strength

The magnetic field is measured in Tesla, named after the well-known scientist Nikola Tesla, and the CGS unit is Gauss. One Tesla is given as N/m.A, that is, the force required for a charged particle to cross a unit length per ampere; which is the same as the magnetic flux.

The intensity of the magnetic field is current flowing per unit length of the conductor and is measured in terms of Oersted which is also represented as Ampere per meter.

Frequently Asked Questions

What is the reason behind the formation of a magnetic field of the Earth?

The magnetic field of the Earth prevents the ionized debris approaching from the Sun to enter the Earth’s atmosphere imparting a shield, thus guarding the atmosphere and existence on our planet.

The Earth’s core composes of the majority of Iron (Fe) which is ferromagnetic. As the molten lava is denser than the plates floating on the asthenosphere, the molten lava composed of Iron and nickel penetrates towards the core of the Earth. Due to the glide of molten iron, the convection current is generated that produces a magnetic field.

What is the range of magnetic field produced in a Magnetic Resonance Imaging (MRI) machine?

Magnetic resonance imaging machines are widely used in the hospital to take pictures of the anatomy of organs in the human body to take precise details.

The magnetic field produced by an MRI machine is in a range of 0.5 Tesla to 2.0 Tesla i.e. 5000 Gauss – 20,000 Gauss; whereas the value of the Earth’s magnetic field is just 0.5 Gauss.

Does the magnetic field of the Earth change frequently?

By studying the rock samples and using the radiometric dating techniques, it is viable to determine and calculate the magnetic field strength and the direction of the field of the Earth varied even for the past millions of years ago.

Yes, the magnetic field strength of the Earth changes frequently as the geo-tectonic activities are predominant and the oceanic crust forming alongside the mid-oceanic ridge indicates the imprints of the magnetic field during that precise time on the rock. The motion of the plates on molten magma gives the idea of the strength of the magnetic field.


Hi, I’m Akshita Mapari. I have done M.Sc. in Physics. I have worked on projects like Numerical modeling of winds and waves during cyclone, Physics of toys and mechanized thrill machines in amusement park based on Classical Mechanics. I have pursued a course on Arduino and have accomplished some mini projects on Arduino UNO. I always like to explore new zones in the field of science. I personally believe that learning is more enthusiastic when learnt with creativity. Apart from this, I like to read, travel, strumming on guitar, identifying rocks and strata, photography and playing chess. Connect me on LinkedIn -

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