The flow of electrons through a conductor creates an electrical current. By definition, two essential factors facilitate an electric current.
First, you’ll need a flow of electrons, which is done by a potential difference. The next is a conductor which is a material that enables electrons to flow.
But why does electricity need a conductor to travel a distance? Why doesn’t it simply flow through any material? Let’s review!
How does electricity flow through a conductor?
To understand the need for a conductor, we must first understand how electrons move through a conductor and how they behave in an insulator.
In a conductor, weak electrostatic forces can sway the electrons in the outermost shell, also called the orbit. This means that the nucleus of the atom is not strong enough to keep all the electrons within the atom.
When we apply an electric potential or EMF (Electro Motive Force) at the ends of a conductor, the poorly held electrons break free from the atoms and start moving within the conductor. This flow of electrons creates an electrical current that carries the electrical energy from the EMF source.
If we take the case of copper, each copper atom has 29 electrons. The first shell or the innermost shell of the copper atom has 2 electrons.
The second shell has 8 electrons, which is the maximum that the shell can accommodate. The third shell has 18 electrons, and the outermost shell has only 1 electron.
This arrangement makes the electron in the outermost shell very mobile and responsive to electrical fields. It is also the reason why copper is an excellent conductor of electricity.
What makes an insulator?
An insulator is the opposite of a conductor where the material doesn’t have many free electrons to move in between. This happens when the electrons in an atom are tightly held by the nucleus, making them highly resistant to the effects of an EMF.
So, conductivity primarily depends on the atom and its characteristics.
How is a resistor different from an insulator?
Resistors find wide applications in electrical circuits to control the current flow. But if conductors enable the flow of electricity and insulators block the same, what is the purpose of resistors?
Resistors scale down the electric current passing through a circuit by restricting the flow of current. Unlike an insulator, the resistor does not block the flow of electrical current.
It just restricts the flow of electric current to a certain degree. And you can fine-tune the level of resistance of a resistor as there are different tiers for resistors.
What makes metals good conductors of electricity?
As we discussed above, the flow of electricity is only possible if there are electrons moving around in the material. The outermost shell of an atom is one of the best ways to determine the conductivity of a material.
Metals have an incomplete outer shell. This means that the outer shell of the metal atom has fewer electrons than it can fully populate. So, these electrons are free to move within the metal simply by applying enough electromotive force.
Materials like rubber have a tightly bound outer shell in their atoms. So, even if you apply a large enough EMF on the material, it would not allow the atoms to flow.
This is the reason why we use derivatives of rubber or plastic to insulate copper wires.
Generally speaking, materials that have a complete outer orbit or shell are good insulators. And materials with less than four outer electrons are excellent conductors.
Metals have less than 4 electrons in their outermost orbits.
How do electrons flow within a conductor?
When we use the term “flow” with electrons, it sometimes leads to a misinterpretation that electrons from one side of the conductor will flow to the other, while the conductor itself acts as a highway. However, this is not how electrons move within the conductor.
The electron released from one atom will move to the outer shell of the adjacent atom. This movement creates instability within the atom leading to a disproportionate number of electrons and protons.
Therefore, an atom from the outermost shell jumps to another adjacent atom. And this process keeps on repeating.
Hence, an electron from one side of the conductor doesn’t directly go to the other side. Instead, it moves to another atom and causes the outer shell electron of that atom to move to the next.
Does electron flow occur in conductors without EMF?
Yes, even without EMF, the valence electrons in a conductor are in a constant state of movement from one atom to another. However, the direction of the electrons is in random order.
Thus, the overall charge of the conductor gets canceled out, hence zero.
What are the best electrical conductors?
We use copper in most electrical applications. However, the best electrical conductor is Silver.
Silver has a total of 47 electrons with one valence electron in the outermost shell. The high energy of this electron makes it vulnerable to movement even from a very small EMF.
This characteristic of silver makes it a great conductor. However, due to the high price, the use of silver in electrical applications is limited.
Gold is the third most efficient conductor. It has 79 electrons with one valence electron in the outermost shell.
The human body is also a good conductor of electricity because of the ions (potassium, sodium, iron, etc.) present in it. These ions are freely moving through bodily fluids and make our bodies susceptible to electrical charges.
Electricity is undoubtedly an exciting and intriguing phenomenon. However, without conductors, it wouldn't be possible to use this energy the way we do today.
Conductors are the bridges for electricity, and they work to keep our devices powered on and ready to use.