Electric current is an electric charge that flows in a conductor per unit time. In electrical science it is known as two types of currents namely Conventional and Electron Current. What is the difference between these two currents and how can an electric current flow in a conductor?
Before we discuss electric current, in 1750 an American scientist named Benjamin Franklin put forward the theory of electricity. He equates electricity with a liquid that cannot be seen by the eye. If the container contains liquid from normal conditions, the container is said to be positively charged and if the container lacks liquid from normal conditions, the container is said to be negatively charged. From this theory, Benjamin Franklin concluded that electric charge flows from positive to negative.
This theory was used until 1897 in various experiments and was known as conventional currents, namely flow from positive to negative. In 1897, Joseph John Thomson (J.J Thomson) discovered British electrons and he proved that these electrons were negatively charged. Now famous for the concept of an atom surrounded by electrons, like a planetary system, the sun is surrounded by planets Mercury, Venus, Earth, Mars, and so on.
In copper conductors, for example, only free electrons can flow from the copper base to the copper end due to the influence of the electric field. From this phenomenon electric current flows from negative to positive. This is contrary to Benjamin Franklin’s statement which states that the current moves from positive to negative.
Then why nowadays most people still use conventional principles today that move positively to negative? Not Electron Current? If we look at the atomic structure, it doesn’t matter if we say an electric current flows from positive to negative or vice versa even though the truth is that electrons can flow.
An atom has several electrons, for example silicon atoms have 14 electrons. If the atom is exposed to an electric field, the electrons on the outermost path can be separated from the trajectory. These released electrons are called Free Electrons and leave an empty space of these electrons called the Hole. The higher the electric field, the more electrons are released from the trajectory. Because this electron has a negative charge, the hole is said to have a positive charge. The free electron will continue to jump to fill the next hole and leave the previous hole. If we see that the negative charge of the free electron will move towards the positive charge Hole and the Positive Hole charge as if it is moving to the right to get free electrons. So from this situation conventional currents can be used to express the movement of electric current from positive to negative, Hole as if moving towards the electron.
Electric current is measured based on the number of free electrons passing through a circuit. Therefore, the flow of per-second electric charge is interpreted as the amount of electric charge. If an electric charge moves in a conductor with the number of free electrons passing through it as much 6.25×1018 atau 6.250.000.000.000.000.000 free of electrons per seconds, then the current value is 1 Ampere. 1 Coulomb is an electric charge containing as much as 6.25×1018 elektrons. It can also be said that 1 Ampere is 1 Coulomb per 1 Second.
In SI (International System of Units), units of electric current are amperes with a capital letter symbol A. A constant current has a symbol I, where a time variation is symbolized by i for intensity. Mathematically we can interpret the relationship between electric charge (Q) and electric charge (I) as follows:
I = Q / t or I (Flow) = Q (electric charge) divided by t (time)
According to the custom that applies the flow of electric current in a circuit is from positive to negative. But actually the flow of electrons in a conductor moves from negative to positive. The arrow in a circuit shows the direction of a positive current flow.
In metal materials only the negative charge of the free electron moves to produce a current, the positive proton cannot move. But in a liquid or gas, both of the positive protons and negative electrons move to produce an electric current.
Since electrical circuits consist almost entirely of solid metal conductors such as copper wire, only the negative charge of electrons produces a flow of electric current. Flow is also a measure of how the strength or concentration of electrons through conductors.