An Overview On Bound Charges In Dielectric

Charges are the free movement of a subatomic particle, i.e., electron or proton within a conductor, towards its surface. When we apply an electric field to these metallic conductors, the electrons get detached from the atom and start moving freely inside the metal. This free movement of electrons inside a metallic conductor is called a charge. Charges inside a conductor always try to reach the surface. Now, it is important to know what is bound charges and bound charges in the dielectric. Bound charges roughly mean particles that are part of an atom or molecule rather than being free-flowing. In the most common terms, electrons are referred to as bound charges, but often, even protons are considered.

What is a Dielectric?

A dielectric is an insulating material, or it can be called a material that is a very poor conductor of heat and electricity. In a dielectric material, no current flows through them even when they are placed in an electric field. This phenomenon occurs because dielectric materials do not have free-flowing electrons inside them.

In a dielectric material, electrons are strongly bound to each other; thus, they cannot have a free flow. Whereas in a good conductor material, electrons are freely bound, and thus, they can travel from point “a” to point “b”, creating an electric charge.

Since in a dielectric material, there is no free flow of electrons, and hence no charge is created in them, polarisation occurs in dielectric materials. Further, we will study what is bound charges in a dielectric material.

Bound Charges in Dielectric

A conductor has a free flow of electrons in them, causing the charge, whereas in a non-conductor (insulator) or, as we call electromagnetism, a dielectric material since the electrons or charges are bound, no electrons can freely move and are bound to the specific atoms and electrons. These charges are known as bound charges. The charges inside a dielectric that are strongly bound to the atoms are called bound charges in the dielectric.

Polarisation in a Dielectric

However, a dielectric material has very tiny displacements and charges inside it. These charges, however, have very tiny movements. These tiny movements and dis-placements are so small that they are microscopic. The microscopic displacements in a dielectric are not as strong as that of a conductor, but when we consider their overall and cumulative effect, we can define them as characteristics of a dielectric. 

When we apply an external electric field to a dielectric material, it becomes polarised. This phenomenon is called the polarisation of a dielectric material. Bound charges in a dielectric are very different from charges in a good conductor.

Bound Charges Definition

Although different books and different authors choose to give bound charges definitions in their own specific ways, the meaning of all of them remains mostly the same. We can define bound charges as the conductor’s electrical charge’s portion that will not be able to escape to the earth due to the neighbouring charge’s inductive action when it is grounded. Moreover, the bound charge is bound to the nucleus, and it can possess only quantized energies. Thus, it possesses both potential and kinetic energy. But, the potential energy is always greater here.

Conclusion

Unlike charges in a conductor that has freely moving and loosely bound electrons, an insulating material has strongly bound and barely moving electrons. These materials, which have barely moving electrons, are called insulators or dielectrics in electromagnetism. Although these dielectrics do not have free electron movement within them, they have tiny microscopic movement inside them when an external electric field is forcibly applied. This tiny, microscopic movement is called polarisation in a dielectric material. We define bound charges in the dielectric as a part of the electric charge in a conductor that will not escape even when it is grounded.