Free Charges and Bound Charges

A charge is a property associated with and related to matter. It experiences different electrical and magnetic effects. The SI unit of an electric charge is called Coulomb. Electric charges in the conservation of charge were first defined by Coulomb. This article is an introduction to the concept of free charges and bound charges and how they create electric currents.

Free charge: Definition

The free charge present in a material cannot create a bound with the nucleus. Moreover, it can hold any amount of energy that can rate from 0 onwards. This type of charge, however, remains in the stage of kinetic charge. 

Free charge: Density

The density of the free charge ensures a positive simplification in Gauss’s Law that is applied in electricity. Furthermore, the volume of this is the amount of free charge present in a material that is charged with electricity. This is further equal to the net flux of the electric displacement field D that further emerges from the body of the material.

Bound charge: Definition

In contrast to free charges, a bound charge has the capacity to bound with the nucleus and further can hold the quantized energy. This type of material that has the capacity to have the bound charge includes both the kinetic and the potential charge in nature. Also, in these materials, the remaining potential energy is always greater than anything. 

Bound charge: Density

Normally, the bound charge is available in the dielectric medium and can be denoted with the help of the dipole incidence that is perpendicular to the surface. This further means: 

qb = p.n/[s]

Here, 

• s = The separation of charge points that is present in the dipole. 
• p = Electric dipole moment
• n = Unit normal vector present on the surface

Thus, from the above discussion, we can find:

dqb.= dp.n/[s]

By diving this with the surface elements, you can further get the surface charge density:

σb = dqb/dS = dp.n/[s]dS.n = dp.n/dV = P.n. 

Here, P represents the polarisation density, which is also defined as the density of the bound charges present in dielectric materials. 

What are dielectric materials? 

A dielectric material is a very poor conductor of heat and electricity. When dielectric mediums are provided in an electric circuit, the flow of the charges does not take place. Unlike metals and other good conductors of electricity, they do not possess any loose free charges or bound charges. For this reason, dielectrics are used as insulating materials. On the other hand, the presence of electric polarisation can be further witnessed. 

The positive charges present in dielectric materials can occur in the direction of the electric field; on the other hand, the negative charge is witnessed in the opposite direction of the electric field. This difference of movement of the charge helps to lower the amount of charge in the dielectric materials. 

Also, the presence of dielectric mediums can hamper the proper flow of the electric charge and can thus hamper the free charges and bound charges. The two electric currents that have the flow in between are dielectric materials that are not high as it is seen in a vacuum. However, the amount of charge it can store is higher. Also, the capacitances in these are greater and can prove a large, scale and macroscopic phenomenal electrical current. 

Define polar molecules

Polar molecules contain a positive end on one side of the molecule with the other end of the negative. On the other hand, the diatomic molecule that holds polar molecules creates the polar covalent bound among the materials. Also, the poles are defined as the two electrically charged areas that are situated on one or the other.  The poles of the polar molecules are further highly equal to the magnet that holds the north and the South Pole. On the other hand, the two poles present in the Polar Molecules are considered as the dipole.

Furthermore, polar molecules generate themselves in the presence of an electric field that holds the positive points of the particles and further gets attracted towards the negative end. 

The polar molecules further move randomly in the first stage where there is no presence of heat and electricity, but when the change is applied then it acquires a special direction due to the attraction provided by the opposite charge.

Define non-polar molecules

Non-polar molecules do not contain any electrical current in the end as the electrons present in them are distributed in a fine manner. The distribution further can be cancelled symmetrically for further distribution. Thus, non-polar molecules cannot be mixed with polar molecules. 

For instance, the non-polar molecules can include oil. However, on the other hand, water is a polar molecule. And also, these liquids cannot create a solution and cannot be mixed as well. Thus both are highly different from each other. 

Conclusion

These are some small studies regarding the free charges and bound charges belonging to its various dimensions present in the object in the form of deformation. This is a vast topic to discuss thus we also provided similar articles like this so that you can have a clear knowledge of the free charges and bound charges. Also, a complete review along with the previous year’s question paper and expert’s methods are provided. The diagram further explains how the Free charges and bound charges work and form when the electric current is obtained by the material.