Electric Flux Density Notes for Electrical Engineering

In this article, you will find the Study Notes on Electric Flux Density which will cover the topics such as Electric Flux, Electric Potential, Dipole Moment, Electric flux lines and Electric field due to Dipole. 

Electric Flux

It may be defined as

 

Where D is electric flux density and it can be given as

D = ε₀ E = Electric flux density (C/m²)

 where, ε₀ = Permittivity of the vacuum = 8.854 × 10^–12 F/m

Electric Potential

The Work done per unit charge or potential energy per unit charge is known as potential difference.

 Electric field intensity can be given as the negative potential gradient of electric field i.e,

E = –∇V

Electric field is irrotational or conservative in nature i.e., ∇ × E = 0

Note: Electric dipole is formed when two points charged of equal magnitudes and opposite polarities are separated by a small distance.

 Dipole Moment

p = Q d Coulomb-metre

where, d is the distance vector from –Q to Q.

 Electric field Intensity at a Point due to a Dipole

An electric dipole or simply a dipole consists of two point charges of equal magnitude and opposite sign, separated by a very small distance.

p = Ql

 Field due to Dipole

The field due to a dipole at a very large distance from the dipole.

where, p = Ql

and a_r, aθ = Unit vectors

Electric Flux

The electric field at any distance r from a point charge in a free space.

 Newton/Coulomb

With E as vector in free space, ε₀E is designated by a symbol D; called electric flux density

D = ε₀ E

The integral of the normal component of the vector D over a surface is defined as the electric flux over the surface.

Electric Flux Lines

An electric flux line is an imaginary path or line which is drawn in such a way that its direction at any point is same as the direction of electric field at that point. The electric flux density (D) is always tangential to electric flux lines. Electric flux lines are also called electric lines of force.

 

Electric field emanates (or originates) from a positive and terminates (or ends) on a negative charge.

An equipotential surface is a surface on which potential remain same throughout the surface and there is no potential difference. The flux line or force line for an equipotential surface is known as an equipotent line on equipotential surfaces or equipotential lines, the potential difference between any points A and B is always zero.

Electrostatic Energy Density

All the Best.