Is Magnetic Flux Negative: 7 Essential Facts You Should Know

The magnetic flux through a surface is the surface constituent of the standard components of the magnetic field B across that surface. It is typically represented by the symbol Ø or ØB. The S.I unit of magnetic flux is Weber, and the CGS unit is the Maxwell. Magnetic flux is generally calculated by a flux meter.

Magnetic flux estimates the entire magnetic field that proceeds along a given area. Magnetic flux is an advantageous device for illustrating the effects of the magnetic force on anything inhabiting a given area. The calculation of magnetic flux is fixed to the specific area selected. If the magnetic flux is negative, the activated electromotive force always resists the variation in magnetic flux combined with a contriving loop.

Can magnetic flux be negative?

Yes, magnetic flux can be negative. Magnetic flux only relies upon where the field is proceeding. Let us consider the sheet and magnetic flux flowing along it from the front line to the back line. Then we can say that the change there is positive and negative in a different way round.

Is magnetic flux negative
Magnetic field lines in magnetic flux image credit: pixabay

It is damn distinct from the statement of Len’s law why the electromotive force described is considered negative: an activated electromotive pressure is always brought about to a current whose magnetic field withstands the actual variation in magnetic flux. Primarily the magnetic field generated because of activated current resists the magnetic flux generating the current itself.

Len’s law illustrates the negative magnetic flux. Len’s law obeys that the induced electromotive force permanently reverses the difference in magnetic flux interrelated with an administrating loop. Regarding physicality, the negative magnetic flux is the same amount as the positive one, aside from the direction in space in reverse.

When is the magnetic flux negative?

The magnetic flux is negative when the ordinary specks are in the reverse supervision of the field, then Ɵ= 180 degrees, and the flux is demise as negative. If the magnetic field is aiming contrary to the maintenance of the surface area, then the value of this flux will be negative.

Magnetic flux can also be negative when the magnetic flux leans on where the magnetic field is advancing. If we have a layer and a magnetic field grows from back to forward, we can announce the flux there as negative. From experiments, the experiment recognized that an abnormality in the magnetic flux actuated a current in the curls whose magnetic field ride out the difference in magnetic flux.

is magnetic flux negative
Magnetic flux leans on where the magnetic field is advancing hence the magnetic flux is negative image credit: pixabay

magnetic flux can described as:

Magnetic flux = B*S*cos(theta)

Both magnetic induction B and surface S are vectors, so we have to dispense with the dot products of two vectors. That might be negative as cos(theta), where theta is the slant between the supervision of the magnetic field and the spatial unit vector interrelated to an unstable surface, changes between -1 to +1.

Why is the magnetic flux negative?

Magnetic flux is negative because Len’s law elucidates the negative sign. It reveals that persuaded electromotive force invariably repels the modified magnetic flux united with directing coiling. Display exercise upon this post. Magnetic flux is a scalar quantity whose positive or negative sign designates the supervision of a magnetic field.

The magnetic flux is negative because an activated current continuously streams in the supervision that debates the swap that created it. More explicitly: an activated current every time persuades the control that produces a magnetic field that resists the generated variation.

The swap is in the magnetic field that created the current. The erratic movement of the magnet varies the magnetic flux (example is MRI), which activates the current—the current travels in a reverse orientation of the magnet. Hence the magnetic flux is negative due to the reverse direction.

is magnetic flux negative
The erratic movement of the magnet varies the magnetic flux (example is MRI) image credit: pixabay

How is the magnetic flux negative?

Consider a circuit and insert a conducting rod that completes the circuit. As it collapses, the magnetic flux diminishes, and a current is activated. The current travels right to left in the rod, which means the current flows in a counter-clockwise direction along the circuit, which withstands the motion of the rod.

Conducting rod is inserting in the circuit

The magnetic field is limited to a rounded region, so for uniformity, we select the assimilation path as a circle of radius r. The immensity of the activated electric field at every point in a process is identical. As stated in Len’s law, the supervision of E must be such that it might operate the induced current to generate a magnetic field that repels the variation in magnetic flux.

The area vector aiming out of the page and the magnetic flux is negative or inbound. The negative sign utilized in Len’s law illustrates that the electromotive force generated in the coil is in such orientation that it withstands the difference in magnetic flux associated with the ring.

What is a negative magnetic flux density?

Magnetic flux density is the notations of the magnetizing field of force that intersects along with an actual point upon a surface. The S.I unit of magnetic flux density is Tesla(T), which is Weber per square meter(Wb/m2), and the unit in the CGS system is Gauss(G). Magnetic flux density is typically expressed by the symbol vector B.

A magnetic field at each one of the obsessed points can be detected as a vector in the trajectory of the area with an enormity equal to the Lorentz force enforced on an electric wire fall into line stand up to the lines of force, announced in ampere per meter. The greater the flux density, the stronger the magnet will be at that point; hence, the good it can clasp iron particles.

Magnetic flux density (B) is nothing but the quantity of magnetic force prompted on the given body because of magnetizing force H. The amount of pressure magnetic started relies on the strength of H and the creation of an intermediate of a given body. Both B and H do designate the power of magnetic field H.

Is magnetic flux always negative?

No, the magnetic flux is not always negative. It depends on where the magnetic field is going, whether it may be positive, negative, or zero. The magnetic flux is a scalar quantity or dot product, and a positive or negative sign elucidates the positioning of the magnetic field.

For an object in a uniform and non-uniform magnetic field, exterior flux is considered positive, and interior flux is assumed to be negative. The magnetic field can or cannot be zero if the magnetic flux ƟB=0. A positive flux might be equal to an adverse change. But if = 0, the flux will compulsorily zero.

Magnetic flux is measured over an area surrounded by an impermeable curve. An element of space is a vector at right angles to the surface element. The direction of the region relies through the Right-Hand Rule on the orientation that the configuration curve succeeds.

So, when the magnetic field is collateral to the area vector, the integral of magnetic flux is positive. The change will be negative when the area and the magnetic field are anti-parallel.

When is the magnetic flux positive?

The number of magnetic lines of force flowing along a definite area imprisoned transverse to it is said to be the magnetic flux. Magnetic lines of force departure away from the substantial element are considered positive. Magnetic lines of force that come into the definite factor are generally regarded as negative.

Magnetic flux is said to be positive when Ɵ=0 degrees. A typical plane may be peaked from each of two sides. If the regular peak to a plane points away in the field’s orientation, then Ɵ=0^o, and the flux is considered positive. If the change is positive and developing, the voltage would be negative.

The magnetic flux is positive when it goes away from the sealed surface. Flux relegates in the surface enormity, the dimension of the magnetic field, and the inclination between the surface and the magnetic field. The magnetic flux is positive when the field vectors proceed in the same orientation as the vectors typical to the surface.

Frequently asked questions

What is the difference between magnetic flux and flux density?

Suppose we can have a larger magnetic field that contains a magnetic flux. Although, magnetic flux could disseminate it across a tremendous area. It might be in the air, or it could be in the iron core. For this vast field to work for us, we should regulate its density in how many lines of magnetic force are in a definite area. That is flux density.

It is a segment like we have a mass of 100 pounds. That mass can be over a squared kilometer or an infrequent square millimeter or square inch. That establishes compulsion for a given area.

The greater magnetic field is scattered over a considerable space in the air. Its flux density is minimum or low. But in the iron core, the equal number of lines of magnetism would accommodate too much lesser area due to magnetic lines wanting to move along iron a lot more than air. Hence the flux density could be much more significant.

is magnetic flux negative
Magnet and the iron core image credit: pixabay


Magnetic flux calculates the whole magnetic field that flows along a given area. It is a Utilitarian device for relieving illustrating the consequences of the magnetic force on anything acquiring a given site. The magnetic flux may be positive, negative, or zero, depending on the direction.

Megha BR

Hi, I am Megha B R, I have completed my Post-Graduation in Solid State Physics and pursuing B. Ed. I am a Physics enthusiast. As an Academic writer, my goal is to reach the readers in a simplified manner through my articles.

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