# What is the relation between electric field and dipole moment?

## What is the relation between electric field and dipole moment?

An electric dipole in an external electric field is subjected to a torque τ = pE sin θ, where θ is the angle between p and E. The torque tends to align the dipole moment p in the direction of E. The potential energy of the dipole is given by Ue = −pE cos θ, or in vector notation Ue = −p · E.

## How is surface charge density related to electric field?

Since electric charge is the source of electric field, the electric field at any point in space can be mathematically related to the charges present. The divergence of the electric field at a point in space is equal to the charge density divided by the permittivity of space.

What is the relation between surface charge density and induced surface charge density?

The total charge is obtained by multiplying by the electronic charge qe. To get the surface density of the polarization charge induced on the surface, we divide by A. The magnitude of the surface charge density is σpol=Nqeδ. But this is just equal to the magnitude P of the polarization vector P, Eq.

### What is dipole moment density?

In classical electromagnetism, polarization density (or electric polarization, or simply polarization) is the vector field that expresses the density of permanent or induced electric dipole moments in a dielectric material.

### What is dipole in electric field?

A pair of electric charges with an equal magnitude but opposite charges separated by a distance d is known as an electric dipole. The electric dipole moment is a vector having a defined direction from the negative charge to the positive charge. …

What is dipole moment electric field?

In an electric field a dipole undergoes a torque, tending to rotate so that its axis becomes aligned with the direction of the electric field. The electric dipole moment, a vector, is directed along the line from negative charge toward positive charge.

#### How is electric charge density calculated?

Charge density for volume \rho = 2 C per m^3. Q. 2: A long thin rod of length 50 cm has a total charge of 5 mC, which is uniformly distributed over it.

#### Can electric field exist without charge density?

The an electric field can exist without a charge. BUT it cannot ORIGINATE without charge. EM waves comprise of electric and magnetic field in transit. The electric field here exist without the presence of any charge.

How do you calculate surface charge density?

Surface charge density is a measure of how much electric charge is accumulated over a surface. It is calculated as the charge per unit surface area. If q is the charge and A is the area of the surface, then the surface charge density is given by; σ=qA, The SI unit of surface charge density is Cm–2.

## What is the unit of surface charge density?

Surface charge density (σ) is the quantity of charge per unit area, measured in coulombs per square meter (C⋅m−2), at any point on a surface charge distribution on a two dimensional surface.

## Why is it called a dipole moment?

The Principle of moments is if an object is balanced then the sum of the clockwise moments about a pivot is equal to the sum of the anticlockwise moments about the same pivot. So simplifying, I thought it was called a dipole moment because it describes the range of motion of the molecule.

Which is an idealization of the electric dipole moment?

The electric dipole moment vector p also points from the negative charge to the positive charge. An idealization of this two-charge system is the electrical point dipole consisting of two (infinite) charges only infinitesimally separated, but with a finite p. This quantity is used in the definition of polarization density.

### How is the dipole moment of two point charges expressed?

Elementary definition. A stronger mathematical definition is to use vector algebra, since a quantity with magnitude and direction, like the dipole moment of two point charges, can be expressed in vector form where d is the displacement vector pointing from the negative charge to the positive charge.

### How is charge density measured in electromagnetism?

In electromagnetism, charge density is a measure of the amount of electric charge per unit length, surface area, or volume. Volume charge density (symbolized by the Greek letter ρ) is the quantity of charge per unit volume, measured in the SI system in coulombs per cubic meter (C•m−3), at any point in a volume.

How is a dielectric sphere in a uniform electric field?

Dielectric sphere in a uniform electric field A dielectric sphere of radius a and permittivity is placed in a region of space containing an initially uniform electric field