Magnetic Flux Vs Magnetic Field: Different Aspects and Facts

We often get confused between Magnetic flux and magnetic field. Here in this article, we will discuss differences, similarities, and other interesting facts about magnetic flux vs magnetic field   

Magnetic flux and magnetic field both are characteristics of a magnet. The major distinction among magnetic flux and the magnetic area is that magnetic area is area close to the magnet or current-sporting conductor wherein magnetic pressure may be felt, on the alternative hand, magnetic flux is the range of magnetic area traces passing via an area. 

Magnetic field   

A magnetic field is an area in space where mobile ions and magnetic polarities are subjected to a force (Considering the lack of electric field, because that also exerts force).   

The force felt is proportional to the intensity of the magnetic area. Magnetic field lines may be used to symbolize a magnetic field. Magnetic field lines are brought nearer together under a greater magnetic field.  

On the magnetic field line, an arrowhead can be made such that the field lines flow in the direction of a north pole positioned in the magnetic field. Placing metal particles in a magnetic field and letting them line up produces the form of magnetic field lines.  The force experienced by a particle of charge q moving through the magnetic field at a velocity may be used to describe the magnetic field intensity;  

F= qv * B

If the magnetic field and motion of particles are perpendicular to each other, then we get   

F= qvB

When the word “magnetic field” refers to a quantity rather than a place, it is almost always refers to the magnetic field strength. The Tesla is the SI unit for measuring magnetic field intensity (T). The depth of the Earth’s magnetic field varies through location, however it’s far at the order of microteslas.

The quantity of magnetic subject that passes throughout an area is measured with the aid of using magnetic flux. Magnetic flux is described as the “number” of magnetic subject strains journeying thru a given area in a simplified manner. The term “magnetic subject” refers to a place wherein a magnetic pressure can be experienced. The magnetic subject is totally depending on the magnet that generates it. Magnetic fields of a few teslas are produced by magnets used in MRI equipment in hospitals, and the highest magnetic field we’ve been able to build is roughly 90 T.  

Magnetic flux  

The quantity of magnetic subject that passes throughout an area is measured with the aid of using magnetic flux.  As a result, this amount is affected not only by the strength of the magnetic field but also by the size of the region.  Magnetic flux is described as the “number” of magnetic subject strains journeying thru a given area in a simplified manner. 

The precise definition of magnetic flux, on the other hand, is presented via vector calculus. The magnetic flux Φ is calculated by integrating the magnetic field across a surface in this way;   

Φ = ∫B.dA

If magnetic field of strength B passes normal to an area A, the above equation simplifies into this  

Φ = BA

SI unit of magnetic flux is Weber (Wb). 1Wb= 1T m2

The net magnetic flux across a closed surface, according to Gauss’s equation of magnetism, is zero. This indicates that magnetic field lines make complete loops, and thus a north pole without a south pole, and vice versa is impossible. Even though no research has yet identified them, some hypotheses anticipate the presence of so-called “magnetic monopoles.”  

The magnetic flux is, if we use a typical smooth surface with area A as our testing area and that there is an angle θ between the normal to the surface and a magnetic field vector (magnitude B).  

Φ = B A cosθ

where A , the area vector, is described as a vector perpendicular to the loop’s plane with a magnitude equal to the loop’s area AA . The area vector is measured in m2 in SI units. 

The angle is 0 when the surface is perpendicular to the field, and the magnetic flux is simply BA. 


Magnetic flux vs magnetic field

S. no. Magnetic flux Magnetic field 
1.The amount of magnetic field lines that flow through a certain region is referred to as magnetic flux.   The term “magnetic subject” refers to a place wherein a magnetic force can be experienced. 
2.Magnetic flux is influenced by the area and direction of a region as well as the magnet that generates the field.   
The magnetic subject is totally depending on the magnet that generates it. 
3.The SI unit of magnetic flux is Weber (Wb).  
1Wb= 1T m2
The Tesla is the SI unit for measuring magnetic field intensity (T).  
4.Φ = BAF= qvB

Magnetic flux vs magnetic field strength  

The amount of the magnetic field in a material that arises from an external current and is not intrinsic to the material itself is known as magnetic field strength, often known as magnetic intensity or magnetic field intensity.  

It is calculated in amperes per meter and is denoted with the aid of using vector H. H is described as

H= B/(mu-M) , in which B is the magnetic flux density, that’s a degree of the actual magnetic field inside a fabric expressed as a attention of magnetic field lines, or flux, per unit cross-sectional area; M is the magnetization.  

The magnetic field H may be assumed of just like the magnetic discipline generated with the aid of using modern-day flowing via wires, at the same time as the magnetic field B may be concept of as the overall magnetic field, which incorporates the contribution M from the magnetic houses of the substances withinside the field. 

The magnetizing field H is weak whenever a current flows in a coiled wire around a soft-iron cylinder, however, the actual average magnetic field (B) inside the iron could be numerous times greater since B is vastly strengthened by the orientation of the iron’s numerous tiny natural atomic magnets in the field’s way.  

Magnetic field and magnetic flux relation

A magnetic field is represented through separate vectors: one known as magnetic flux density, or magnetic induction, is represented through B, and every other known as magnetic field strength, or magnetic field intensity, is represented through H. 

H= B/(mu-M) it shows relationship between magnetic flux density that is B and magnetic field intensity that is H.

Difference between magnetic flux and magnetic flux density   

Magnetic flux is a scalar quantity, at the same time as magnetic flux density is a vector quantity. The scalar is product of the magnetic flux density and the vicinity vector is magnetic flux. Magnetic flux is a constant value on the other hand magnetic flux density is varying quantity. 



Problem 1:

In a homogeneous magnetic field of strength 0.6 T, a rectangular loop with a side length of 4 cm is placed so that the loop’s plane creates a 45-degree angle with the magnetic field. What is the flux that flows through the square loop?

magnetic flux vs magnetic field
Magnetic flux vs magnetic field

Solution: Given values are ;

l = 4cm

B= 0.6T

             Φ = 45°

Placing given values in magnetic flux formula,  

    Φ = B A cos θ

    Φ= (0.6)(0.04*0.04)\cos 45°

    Φ= 0.68mWb

Angle θ = 45° is the angle between B and a unit vector normal to the surface.   

And the given angle θ = 45° is with surface of the loop not with vector normal to the surface that is


Problem 2:

A circular loop of area 200cm2 placed in the xz plane

Then, a uniform magnetic field of B= 0.2i^+0.3j^T applied on it. What is the   

(a) Magnitude of the magnetic field   

(b) Magnetic flux through the square loop?  


(a) The magnitude of a vector such as   

R= Rxi^+Ry j^ is given by the formula ;  

R= Rxi^+Ryj^= √Rxi^2+Ryj^2

so, strength (magnitude) of the magnetic field is determined as  

B= √[(0.2)2+(0.3)2]= 0.36 T

(b) This circular loop is positioned at right angle with the y  axis so a unit vector perpendicular to it is written as             


Now we use the scalar definition of magnetic flux as   Φ =Bn^ to find it as below  

 Φ =Bn^

= 0.2i^+0.3j^c.j^*200*10-4

= (0.2i^c.j^+0.3j^.j * 0.2)

= 0.3*0.2

= 0.06 T

We have used 1cm2= 10-4m2 this conversion rule in above solution.

Frequently asked questions |FAQs   

Q. What is the distinction between B and H?  

Ans. The distinction between B and H is that B represents magnetic flux density whereas H represents magnetic field strength.  

Q. When is the magnetic flux at its greatest?  

Ans. When the magnetic flux across a coil is equal to zero, it is at its peak. As a result, equal this formula to zero and calculate the angle between the coil’s plane and the lines of force.  

Q. On what parameter magnetic flux depends?  

Ans. The magnetic flux is determined by the surface form and the contained current.  

Q. What is the relationship between magnetic field and flux?  

Ans. The magnet has characteristics like magnetic field and flux. The magnetic field is the space where mobile ions are subjected to force, and the magnetic flux indicates how many magnetic lines of force travel through it. A closed-loop is formed by the magnetic lines of force. 

Q. What causes a magnetic field to change?

Ans. The term “change in the magnetic field” refers to a shift in magnetic field intensity
. As we get closer to the magnet, the magnetic strength grows, and as we get further away, it diminishes. As a result, if a magnet is pushed towards or out from an electric circuit, the magnetic field intensity of that moving bar magnet will affect the circuit.

Q. How magnetic field generates currents?

Ans: Current is induced by a shift in magnetic field in the following way:

The above-mentioned shift in magnetic field strength causes emf.The electric potential (voltage) that permits the movement of charges per unit time is known as the electromagnetic field (EMF).The electric current is created by the passage of charges. This current is known as induced current because it is induced by a variation in magnetic field intensity.




Also Read: