Unit of Electric Flux - Definition, Formula, FAQS

Q: What is electric flux density and its units?

Electric flux density Electric flux density is the electric flux passing through a unit area perpendicular to the direction of the flux. Electric flux density is a measure of the strength of an electric field generated by a free electric charge. Unit of electric flux density Electric flux density is obtained by flux passing per unit area. Unit of electric flux density=N/C

Unit of Electric Flux - Definition, Formula, FAQS

Edited By Team Careers360 | Updated on Jul 02, 2025 04:58 PM IST

In this article we are going to learn about Electric flux, S.I unit of electric flux, Electric flux density , Unit of electric flux density and many more.

What is Electric Flux?

An electric field's property is electric flux.

It can be compared to the number of forces that cross a certain area.

Electric field lines are commonly thought to begin with positive charges and conclude with negative charges.

Negative field lines are those that are directed into a closed surface, whereas positive field lines are those that are directed out of a closed surface.
If no net charge exists within a closed surface, every field line directed into the surface passes through the interior and is usually directed outward elsewhere on the surface.

The negative flux just equals the positive flux in magnitude, resulting in a net or total electric flow of zero.

When a net charge is imprisoned inside a closed surface, the total flux through the surface is proportional to the enclosed charge, positive if the charge is positive and negative if the charge is negative.

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Unit of Electric Flux - Definition, Formula, FAQS

Gauss law

Formula shows Relation between electric flux and electric field

Gauss law for the electric field is the mathematical relationship between electric flux and the contained charge.

It's one of electromagnetism's fundamental rules.

The net flux of an electric field through any closed surface is usually equal to the enclosed charge, in coulombs, divided by a constant termed the permittivity of free space in the related meter-kilogram-second system and the International System of Units (SI).

The net flow of an electric field through any closed surface in the centimetre-gram-second system is equal to 4 times the contained charge, measured in electrostatic units (esu).

The number of electric field lines passing through a virtual surface determines the electric flux.

This can be explained using an equation.

The electric flux (ΦE)) travelling through a surface of vector area S if the electric field is homogeneous is:

Φ_E = E⋅S = EScosθ,

where E is the electric field's magnitude (in units of V/m), S is the surface's area and is the angle between the electric field lines and the normal (perpendicular) to S.

The electric flux dΦE through a small surface area dS in a non-uniform electric field is commonly indicated by:

dΦ_E=E⋅dS,

where E denotes the electric field, and A denotes the area component perpendicular to the field.

SI unit of electric flux

Voltmeters (V m), which is also equivalent to newton-meters squared per coulomb, are the SI base unit of electric flux (N m² C^-1)

Furthermore, kg·m³·s^-3·A^-1.is the fundamental unit of electric flux.

We now know that (N m² C^-1) is the SI unit for electric flux.

M = MASS.
L = LENGTH.
T = TIME.
I = CURRENT

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As a result, we know that the SI unit of force ‘N/Newton' is represented in dimension as MLT⁻²

M² represents the SI unit of meter

Length is represented in dimension as L² .
And ‘C’ the SI unit of charge is represented in dimension as M⁰ L ⁰ T ¹ I¹ ,

As a result, the dimensional values are converted to the SI unit of electric flux. (N m² C^-1) we get, M·L³·T^-3·I^-1

Electric flux dimensional formula
Electric flux is a measure of the dispersion of the electric field through a specific surface in electromagnetism.

The electric flux dimensional formula is discussed earlier

[M L³ T⁻³ A⁻¹]

Also Read:

Electric flux density

Electric flux density is the electric flux passing through a unit area perpendicular to the direction of the flux. Electric flux density is a measure of the strength of an electric field generated by a free electric charge.

Unit of electric flux density

Electric flux density is obtained by flux passing per unit area.

Unit of ϕ=Nm²/C

Unit of electric flux density=Nm²/C/m²=N/C

Conclusion

Electric flux is a scalar quantity

The SI unit of electric flux is (N m² C^-1)

The dimensional formula of electric flux is M·L³·T^-3·I^-1

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Frequently Asked Questions (FAQs)

1. What is the si unit of electric flux? Or What is electric flux units?

Voltmeters (V m), which is also equivalent to newton-meters squared per coulomb, are the SI base unit of electric flux (N m² C^-1)

kg·m³·s^-3·A^-1.is the fundamental unit of electric flux.

2. Define electric flux and its si unit?

An electric field's property is electric flux.

It can be compared to the number of forces that cross a certain area.

Electric field lines are commonly thought to begin with positive charges and conclude with negative charges.

Negative field lines are those that are directed into a closed surface, whereas positive field lines are those that are directed out of a closed surface.

If no net charge exists within a closed surface, every field line directed into the surface passes through the interior and is usually directed outward elsewhere on the surface.

The negative flux just equals the positive flux in magnitude, resulting in a net or total electric flow of zero.

SI unit of electric flux (N m² C^-1)

Dimensional formula of electric flux

We now know that (N m² C^-1) is the SI unit for electric flux.

M = MASS.
L = LENGTH.
T = TIME.
I = CURRENT

[M L³ T⁻³ A⁻¹] is the dimension of electric flux.

3. What is electric flux density and its units?

Electric flux density

Unit of electric flux density

Electric flux density is obtained by flux passing per unit area.

Unit of electric flux density=N/C

4. Is electric flux is a scalar quanity?

Yes it is a scalar quantity

5. In a uniform electric field, a planar surface is rotated. When does the electric field flux across the surface reach its peak?

When the surface is perpendicular to the field.

6. When is a positive flow through a surface considered?

The flux lines are directed outwards when the flux lines are directed outwards.

7. What is the SI unit of electric flux?

The SI unit of electric flux is newton-meter squared per coulomb (N⋅m²/C) or volt-meter (V⋅m). This unit is derived from the definition of electric flux, which involves electric field strength (N/C or V/m) multiplied by area (m²).

8. How is the unit of electric flux related to the units of electric field and area?

The unit of electric flux is a product of the units of electric field and area. Electric field is measured in N/C or V/m, and area is measured in m². When multiplied, these give N⋅m²/C or V⋅m, which are the units of electric flux.

9. What's the difference between electric flux and magnetic flux?

While both are measures of field strength through an area, electric flux quantifies electric fields (measured in N/C or V/m) passing through a surface, while magnetic flux quantifies magnetic fields (measured in teslas) passing through a surface. Their units and the fields they describe are different.

10. What's the significance of Gauss's law in electrostatics?

Gauss's law is significant in electrostatics because it relates the electric flux through a closed surface to the enclosed charge. This allows us to calculate electric fields for symmetrical charge distributions without needing to use more complex methods like direct integration of Coulomb's law.

11. What's the difference between electric flux density and electric flux?

Electric flux density (D) is the amount of electric flux per unit area, measured in coulombs per square meter (C/m²). It's a vector quantity. Electric flux (Φ) is the total amount of electric field passing through a surface, measured in N⋅m²/C or V⋅m. Flux is the integral of flux density over an area.

12. What is electric flux and why is it important in physics?

Electric flux is a measure of the electric field passing through a given surface area. It's important because it helps us understand how electric fields interact with surfaces and is crucial in applying Gauss's law to solve complex electrostatic problems. Electric flux provides insights into the strength and distribution of electric fields in space.

13. Can electric flux be negative? If so, what does it mean?

Yes, electric flux can be negative. A negative flux indicates that the electric field lines are entering the surface, rather than leaving it. The sign of the flux depends on the relative orientation of the electric field and the surface normal vector.

14. How does the shape of a surface affect electric flux?

The shape of a surface affects electric flux because flux depends on both the strength of the electric field and the area of the surface. A curved surface may have different amounts of flux passing through different parts, while a flat surface perpendicular to the field lines will have uniform flux across its area.

15. Why is the concept of solid angle important in understanding electric flux?

Solid angle is crucial because it helps us understand how electric flux varies with distance from a point charge. As we move farther from a point charge, the solid angle subtended by a surface decreases, which explains why the flux through the surface decreases with the square of the distance.

16. How does the orientation of a surface relative to the electric field affect the flux through it?

The orientation of the surface relative to the electric field is critical in determining the flux. Maximum flux occurs when the surface is perpendicular to the field lines. As the surface tilts, the flux decreases, becoming zero when the surface is parallel to the field lines.

17. How does electric flux relate to Gauss's law?

Gauss's law states that the total electric flux through a closed surface is proportional to the enclosed electric charge. This relationship allows us to calculate electric fields for symmetrical charge distributions by considering the flux through a carefully chosen Gaussian surface.

18. What's the relationship between electric flux and electric potential?

While electric flux and electric potential are related concepts, they describe different aspects of electric fields. Flux quantifies the field passing through a surface, while potential represents the work done per unit charge to move a test charge in the field. The gradient of the electric potential gives the electric field, which in turn determines the flux through a surface.

19. How does the concept of electric flux apply to electromagnetic waves?

In electromagnetic waves, the electric flux is constantly changing. As the electric field oscillates, the flux through a given surface also oscillates. This changing electric flux, according to Faraday's law, induces a changing magnetic field, which in turn induces a changing electric field, propagating the electromagnetic wave.

20. How does the concept of electric flux relate to the method of images in electrostatics?

The method of images in electrostatics uses the concept of electric flux to solve problems involving conductors. By introducing imaginary charges that create the same flux distribution as the actual charges and conductors, we can simplify complex problems. The flux from these image charges helps maintain the correct boundary conditions at conductor surfaces.

21. How does the presence of a dielectric material affect electric flux?

The presence of a dielectric material reduces the electric flux through a given surface. Dielectrics become polarized in an electric field, creating an internal field that opposes the external field. This results in a reduced net field and, consequently, reduced flux. The reduction factor is related to the dielectric constant of the material.

22. Can electric flux be quantized?

While electric charge is quantized (comes in discrete units), electric flux itself is not quantized in classical electromagnetism. However, in certain quantum mechanical contexts, such as the quantum Hall effect, a quantization of magnetic flux (and by extension, electric flux in dual scenarios) can be observed.

23. How does the concept of electric flux relate to Faraday's law of induction?

Faraday's law of induction states that the induced electromotive force in a closed loop is equal to the negative rate of change of magnetic flux through the loop. While this law directly involves magnetic flux, it's closely related to electric flux. The changing magnetic flux induces an electric field, which creates an electric flux through surfaces in the region.

24. What's the relationship between electric flux and Gauss's law in differential form?

Gauss's law in differential form states that the divergence of the electric field is proportional to the charge density. This is directly related to flux because the divergence of the electric field at a point represents the outward flux per unit volume at that point. The integral form of Gauss's law, which deals with total flux, can be derived from this differential form.

25. How does the concept of electric flux apply to the photoelectric effect?

While the photoelectric effect is primarily explained by the particle nature of light, the concept of electric flux can help understand the electric fields involved. When light strikes a metal surface, it creates an electric field that can eject electrons. The flux of this field through the metal surface is related to the intensity of the light and affects the rate of electron emission.

26. Can you have electric flux in a superconductor?

In a perfect superconductor, there is no electric flux in the bulk of the material. Superconductors expel magnetic fields (Meissner effect), and by electromagnetic duality, they also perfectly shield static electric fields. Any applied electric field is screened by surface charges, resulting in zero field and zero flux inside the superconductor.

27. What's the significance of Gauss's law in integral form in relation to electric flux?

Gauss's law in integral form directly relates the total electric flux through a closed surface to the enclosed charge. It states that the flux is equal to the enclosed charge divided by the permittivity of free space. This form of the law is particularly useful for calculating electric fields in situations with high symmetry, where the flux can be easily determined.

28. How does the concept of electric flux apply to the operation of electron microscopes?

In electron microscopes, electric flux plays a crucial role in focusing and directing the electron beam. The flux of the electric field through apertures and around charged plates determines the path of the electrons. By controlling this flux through carefully designed electromagnetic lenses, the microscope can focus electrons to create high-resolution images.

29. Can electric flux be used to detect the presence of hidden charges?

Yes, electric flux can be used to detect hidden charges. By measuring the flux through a closed surface surrounding a region, we can determine if there are any net charges inside, even if we can't see them directly. This principle is used in various charge detection technologies and is fundamental to our understanding of charge distributions in matter.

30. What's the relationship between electric flux and the work done by an electric field?

While electric flux and work are different concepts, they are related. The work done by an electric field in moving a charge is related to the change in electric potential, which in turn is related to the electric field. The flux of this field through a surface gives us information about the field's strength and distribution, indirectly relating to the work it can do.

31. Can there be electric flux in a region with no electric field?

No, there cannot be electric flux in a region with no electric field. Electric flux is a measure of the electric field passing through a surface, so if there's no electric field, there's no flux. This is why the flux is zero inside a conductor, where the electric field is zero.

32. How does the concept of electric flux apply to Faraday cages?

Faraday cages demonstrate the principle of zero electric flux inside a conductor. The cage, being a conductor, has no internal electric field in electrostatic conditions. Therefore, there's no electric flux inside the cage, which is why it shields its contents from external electric fields.

33. What's the relationship between electric flux and electric field lines?

Electric flux is directly related to electric field lines. The flux through a surface is proportional to the number of field lines passing through it. More field lines crossing a surface indicate a stronger electric field and thus a larger flux.

34. How does electric flux change if you double the area of a surface in a uniform electric field?

If you double the area of a surface in a uniform electric field, keeping the orientation constant, the electric flux will also double. This is because flux is directly proportional to the area when the electric field strength and orientation remain constant.

35. Why is the electric flux through a closed surface containing no charges always zero?

The electric flux through a closed surface containing no charges is always zero because, according to Gauss's law, the net flux is proportional to the enclosed charge. With no enclosed charge, there's no net outward or inward flux; any field lines entering the surface must exit it, resulting in zero net flux.

36. How does the concept of electric flux help in understanding the behavior of electric fields near conductors?

Electric flux helps us understand that electric field lines always enter or exit a conductor perpendicular to its surface. This is because any tangential component would cause charges to move, contradicting the equilibrium state of the conductor. The flux concept thus explains the behavior of fields near conductor surfaces.

37. Can you have non-zero electric flux through a surface in a region of uniform electric field?

Yes, you can have non-zero electric flux through a surface in a region of uniform electric field, as long as the surface is not parallel to the field lines. The flux will be maximum when the surface is perpendicular to the field and will decrease as the angle between the surface normal and the field direction increases.

38. How does the electric flux through a surface change as you move it farther from a point charge?

As you move a surface farther from a point charge, the electric flux through it decreases. This is because the electric field strength decreases with the square of the distance from a point charge. If the surface area remains constant, the flux will decrease proportionally to the square of the distance.

39. How does the concept of electric flux apply to lightning rods?

The concept of electric flux helps explain the effectiveness of lightning rods. The sharp point of a lightning rod creates a region of high electric field strength, resulting in a large electric flux in its vicinity. This concentrated flux facilitates the ionization of air molecules, creating a preferred path for lightning discharge.

40. Why is the electric flux through a closed surface not affected by charges outside the surface?

The electric flux through a closed surface is not affected by charges outside the surface because the field lines from external charges that enter the surface must also exit it, resulting in zero net flux contribution. Only the enclosed charges contribute to the net flux, as stated by Gauss's law.

41. How does the concept of electric flux relate to the inverse square law of electrostatics?

The concept of electric flux is closely related to the inverse square law. As we move away from a point charge, the electric field strength decreases with the square of the distance. However, the surface area of a sphere centered on the charge increases with the square of the radius. These effects balance out, resulting in a constant total flux through any closed surface around the charge, regardless of its size.

42. Can electric flux be used to determine the direction of an electric field?

While electric flux alone cannot determine the direction of an electric field, the sign of the flux through a surface can indicate whether the field is predominantly entering or exiting the surface. Positive flux suggests the field is mostly exiting, while negative flux suggests it's mostly entering. To fully determine field direction, you'd need flux measurements through multiple differently oriented surfaces.

43. How does the concept of electric flux apply to capacitors?

In a parallel-plate capacitor, the electric flux helps us understand the uniform electric field between the plates. The flux entering one plate must equal the flux exiting the other, explaining the equal and opposite charges on the plates. The flux concept also helps in calculating the capacitance by relating the charge on the plates to the electric field between them.

44. Why is the electric flux through a closed surface surrounding a dipole zero?

The electric flux through a closed surface surrounding a dipole is zero because the total charge enclosed is zero. The positive flux from one charge is exactly cancelled by the negative flux from the other charge. This demonstrates that the net flux depends only on the total enclosed charge, not on how that charge is distributed.

45. Can you have electric flux in a vacuum?

Yes, you can have electric flux in a vacuum. Electric flux is a property of the electric field itself and doesn't require a medium. In fact, electric fields and flux often behave more simply in a vacuum because there are no complicating factors like polarization of materials.

46. How does the concept of electric flux apply to Van de Graaff generators?

In a Van de Graaff generator, the concept of electric flux helps explain charge accumulation. As charge is deposited on the dome, it spreads out to maximize the flux leaving the surface. This results in a high electric field near the dome's surface, especially at points and edges where the flux is concentrated, leading to the characteristic hair-raising effect.

47. Why is the electric flux through any closed surface in electrostatics always an integer multiple of 1/ε₀?

According to Gauss's law, the electric flux through any closed surface is equal to the enclosed charge divided by the permittivity of free space (ε₀). Since charge is quantized in multiples of the elementary charge e, the flux must always be an integer multiple of e/ε₀. This fundamental relationship links the quantization of charge to the continuous nature of electric fields.

48. How does the concept of electric flux apply to electrostatic shielding?

Electrostatic shielding works on the principle that electric flux cannot penetrate a conductor. When a conductor completely encloses a region, no external electric flux can enter that region. This is why Faraday cages are effective at shielding: they redirect the electric flux around the enclosed space, creating a field-free region inside.

49. How does the concept of electric flux relate to the principle of superposition in electrostatics?

The principle of superposition states that the total electric field at a point due to multiple charges is the vector sum of the fields due to individual charges. This principle extends to electric flux: the total flux through a surface due to multiple charges is the sum of the fluxes due to each charge individually. This additive property of flux is crucial in applying Gauss's law to complex charge distributions.

50. How does the concept of electric flux relate to the behavior of electric fields at sharp points?

The concept of electric flux helps explain the high field strength near sharp points of conductors. As the surface area decreases near a point, the same amount of flux must pass through a smaller area, resulting in a higher flux density and thus a stronger electric field. This is why sharp points on conductors are often sites of electric discharge.

51. How does the concept of electric flux apply to the design of electrical insulators?

In designing electrical insulators, understanding electric flux is crucial. Good insulators minimize electric flux through their volume, redirecting field lines around them. The shape of insulators is often designed to spread out the flux over a larger surface area, reducing the local field strength and preventing breakdown. This is why high-voltage insulators often have a complex shape with multiple sheds or fins.

52. Can electric flux be used to explain the concept of electric field lines?

Yes, electric flux is closely related to the concept of electric field lines. Field lines can be thought of as representing the direction of electric flux. The density of field lines passing through a surface is proportional to the flux through that surface. This visualization helps in understanding the strength and direction of electric fields in space.

53. How does the concept of electric flux relate to the boundary conditions of electric fields at interfaces?

Electric flux is