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Any electric charge placed on a conductor or within the dielectric or the freely moving charge can be termed a free charge. The opposite of a free charge is known as a polarisation charge or a bound charge. This kind of change is visible when electrons are tightly knit to the nucleus and cannot move freely. The Term ‘Free Charge’ is also used in the advanced analysis and discussions on electricity and electromagnetism. Since the 1890s, The term free charge has been referred to as electricity. It is often applicable in complicated calculations and analysis of electric fields and electromagnetism.
Free Charge Meaning
There are tiny particles known as protons and electrons present in an atom. These particles are electrically charged, due to which they are allowed to have multiple interactions with other charged particles. A positively charged particle is called Proton. It does not move as much and is located in the nucleus of an atom. On the other hand, a negatively charged particle is known as an electron. It can move freely and can orbit the nucleus. Electrons are generally represented as shells around the nucleus. It is to be noted that electrons can move freely in some substances on a much higher scale. For example, electrons present in metals can move freely and even flow into an outer shell or even to another atom. These substances constitute a free charge.
A free charge can also be accelerated under a forceful influence. For example, for a proton to interact with another proton, they will accelerate away from each other. This is because electrons are not held or bound by their parent atoms. It is commonly seen in conductors. On the other hand, insulators have bound charges. These atoms cannot move on a large macroscopic scale.
However, they can move within their atoms. This is how the process of polarisation comes into existence. When an external electric field can exert a force on bound electrons, they all move to one side of the respective atom. This results in the insulator having opposite sides of opposite charges.
Free Charge In A Conductor
Griffiths book’s of electromagnetism states that a free charge in a conductor is always concentrated on the surface, making the electric field negligible inside the conductor. On the contrary, if an electric field is present inside the conductor, there will be a residual force or push to move more charges around until the field gets cancelled.
This surface effect is only present in 3D. Compared to lower dimensions, charges on a plate don’t move to the boundary. When targeting an equilibrium state, in the case of a spherical conductor, a free charge in a conductor comes close to the surface without an electric field. In the presence of an electric field, they move to the surface where the field is directed. Furthermore, in the case of a 2D circular conductor, the electrical charge moves freely inside a conductor. In a downward external field, the electric charges are forced downwards in a frame. In the case of the non-circular sphere, the electric charges go to the surface.
Free And Bound Charges In Electrostatics
In the process of induction, when a negatively charged rod comes in contact with an uncharged sphere, the positive charge begins to move towards the side of the rod and an equal amount of negative charge away from the side of the rod. Therefore, if the negative side of the sphere is earthed, then the positive side will not flow into the ground as it is bound to a negatively charged rod. The charges holding on to something are bound charges.
Conclusion
In the presence of an electric field, the free charge in a conductor is redistributed and attains a speedy electrostatic equilibrium. Further, the resulting distribution of charge and its electric field parameters have varied properties that can be assessed with Gauss’s Law and electric potential. A force is exerted on free electrons if an electric field is present inside a conductor. These are also known as conduction electrons. These electrons aren’t bound to an atom but accelerate. However, Free charge meaning constitutes non-static conditions. Therefore, charges are distributed in a way that the electric field inside the conductor vanishes while attaining an electrostatic equilibrium.
