Chain charge

Phenomenon introduction

The dielectric polarization can generate additional charges in the dielectric inside and on the surface. Since such charge is not available to the free charge in the conductor, it is taken away. Tiny displacement can only be made over the atom or molecular range under electric field force, so reference charge or polarization charge.

It does not take it away like the free charge in the conductor, in the external electric field, the phenomenon of chain charge is called the electrical dielectric.

Polarization intensity relationship

(1) inside the uniform dielectric, the binding charge is abutting each other, and the binding charge is only in the dielectric surface. When the homogeneous medium is polarized, the polarized charge surface density at a certain surface is equal to the component of the electrode intensity of the electrode in the outer stage. All macroscopic effects generated by dielectric are reflected by unsearous binding charges. The relationship between the binding charge distribution and polarization intensity is derived below.

usually defines

as the outer normal direction of the medium.

surface:

Media inside:

Because

,

.

(2) In the non-uniform dielectric, there is accumulation of binding charges. In the electric field, the polarization intensity flux passing through any closed curved surface is equal to the negative value of the total amount of charge in the closed curved surface.

surface:

internal:

.

The negative value of the charge in any surface is equal to the flux of the polarization strength.

Density related relationship

Binding charge body density and polarization intensity

Take a volume of any shape in the medium The side interface of V, V is S, and the polarized charge amount q 'is obtained below.

If V tends to be small physical unlimited, the ratio

is the binding charge body density of this point.

analysis: Those dipoids that are cross-sectioned two sections of the V-side surface are contributed to the polarization charge Q '.

Take a small side DS on S, on

with this point

, and assume

Method to

angle.

DS is small, it is considered to be the same as the above

and believes that the dipole near the DS has equal dipole moment

.

Two sides of DS parallel DS _{1 1 1 1 1 1 1 1 2 2 2 , and the vertical distance of the DS is}

, Obviously, the dipole in the center of the interlayer must be cut by DS, contributing to the polarized charge Q ', and the center of the dipole is associated with the polarization charge Q'.

The number of molecules in the unit volume in the medium is n, the volume of the interlayer is

;

number of dipole numbers within the interlayer (molecule Number of charges contributed by

;

. The amount of charge is

.