A substance that has free particles with a charge moving through the body in an orderly manner due to the acting electric field is called a conductor in an electrostatic field. And the charges of the particles are called free. Dielectrics, on the other hand, do not have them. Conductors and dielectrics have different nature and properties.
Explorer
In an electrostatic field, conductors are metals, alkaline, acidic and saline solutions, as well as ionized gases. Carriers of free charges in metals are free electrons.
When entering a uniform electric field, where metals are conductors without a charge, movement will begin in the direction that is opposite to the field voltage vector. Accumulating on one side, electrons will create a negative charge, and on the other side, an insufficient amount of them will cause an excess positive charge to appear. It turns out that the charges are separated. Uncompensated different charges arise under the influence ofexternal field. Thus, they are induced, and the conductor in the electrostatic field remains without a charge.
Uncompensated charges
Electrification, when charges are redistributed between parts of the body, is called electrostatic induction. Uncompensated electric charges form their body, internal and external tensions are opposite to each other. Dividing and then accumulating on opposite parts of the conductor, the intensity of the internal field increases. As a result, it becomes zero. Then the charges balance.
In this case, the entire uncompensated charge is outside. This fact is used to obtain electrostatic protection that protects devices from the influence of fields. They are placed in grids or grounded metal cases.
Dielectrics
Substances without free electric charges under standard conditions (that is, when the temperature is neither too high nor too low) are called dielectrics. Particles in this case cannot move around the body and are only slightly displaced. Therefore, electric charges are connected here.
Dielectrics are divided into groups depending on the molecular structure. The molecules of dielectrics of the first group are asymmetric. These include ordinary water, and nitrobenzene, and alcohol. Their positive and negative charges do not match. They act as electric dipoles. Such molecules are considered polar. Their electric moment is equal to the finalvalue under all different conditions.
The second group consists of dielectrics, in which the molecules have a symmetrical structure. These are paraffin, oxygen, nitrogen. Positive and negative charges have a similar meaning. If there is no external electric field, then there is no electric moment either. These are non-polar molecules.
Opposite charges in molecules in an external field have displaced centers directed in different directions. They turn into dipoles and get another electric moment.
Dielectrics of the third group have a crystalline structure of ions.
I wonder how a dipole behaves in an external uniform field (after all, it is a molecule consisting of non-polar and polar dielectrics).
Any dipole charge is endowed with a force, each of which has the same modulus, but a different direction (opposite). Two forces are formed that have a rotational moment, under the influence of which the dipole tends to turn in such a way that the direction of the vectors coincides. As a result, he gets the direction of the outer field.
There is no external electric field in a nonpolar dielectric. Therefore, molecules are devoid of electrical moments. In a polar dielectric, thermal motion occurs in complete disorder. Because of this, the electric moments have a different direction, and their vector sum is zero. That is, the dielectric has no electric moment.
Dielectric in a uniform electric field
Let's place a dielectric in a uniform electric field. We already know that dipoles are polar and non-polar molecules.dielectrics that are directed depending on the external field. Their vectors are ordered. Then the sum of the vectors is not zero, and the dielectric has an electric moment. Inside it there are positive and negative charges, which are mutually compensated and are close to each other. Therefore, the dielectric does not receive a charge.
Opposite surfaces have uncompensated polarization charges that are equal, i.e. the dielectric is polarized.
If you take an ionic dielectric and place it in an electric field, then the lattice of crystals of ions in it will slightly shift. As a result, the ion-type dielectric will receive an electric moment.
Polarizing charges form their own electric field, which has the opposite direction with the external one. Therefore, the intensity of the electrostatic field, which is formed by charges placed in a dielectric, is less than in a vacuum.
Explorer
A different picture will develop with the conductors. If conductors of electric current are introduced into an electrostatic field, a short-term current will arise in it, since the electric forces acting on free charges will contribute to the occurrence of movement. But everyone also knows the law of thermodynamic irreversibility, when any macroprocess in a closed system and movement must eventually end, and the system will balance.
A conductor in an electrostatic field is a body made of metal, where electrons begin to move against the lines of force andwill start accumulating on the left. The conductor on the right will lose electrons and gain a positive charge. When the charges are separated, it will acquire its electric field. This is called electrostatic induction.
Inside the conductor, the electrostatic field strength is zero, which is easy to prove by moving from the opposite.
Features of charge behavior
The charge of the conductor accumulates on the surface. In addition, it is distributed in such a way that the charge density is oriented to the curvature of the surface. Here it will be more than in other places.
Conductors and semiconductors have curvature the most at corner points, edges and roundings. There is also a high charge density. Along with its increase, tension is also growing nearby. Therefore, a strong electric field is created here. A corona charge appears, causing charges to flow from the conductor.
If we consider a conductor in an electrostatic field, from which the internal part is removed, a cavity will be found. Nothing will change from this, because the field has not been, and will not be. After all, it is absent in the cavity by definition.
Conclusion
We looked at conductors and dielectrics. Now you can understand their differences and features of the manifestation of qualities in similar conditions. So, in a uniform electric field, they behave quite differently.
