# Electric Current, Unit, and Direction

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## Explanation of Electric Current

Explanation of Electric Current – Electricity cannot be separated from 3 basic parts, voltage, current and resistance. Wherever we work with electricity, we will meet these 3 basics. Therefore it is important to us to understand these three basics.

In this article, I will explain the notion of electric current from the basics. But before that let’s look back at the history of Electric Current.

### History of The Electric Current

In some sources, Benjamin Franklin is the inventor of the first electric current. He is a United States scientist who put forward the theory of electric currents in 1750.

For him at that time, electricity could be equalized to water, but it was invisible or water that was not visible.

If a vessel holds more water and water than the size of the vessel, then the condition is said to be positively charged.

If the vessel is dehydrated from the size of the vessel, then the condition is said to be negatively charged.

From this theory, Benjamin Franklin concluded that electricity flows from positive to negative.

In 1750, J.J. Thomson discovered the electron, the smallest particle of an atom. From this, the direction of the flow of electric current changes from negative to positive.

So the electric current moves from minus (-) to plus (+).

But in practice, we can also assume that the electric current flows from (+) to (-) and this is called Conventional Current.

How did this happen? Come on, see the writing below.

### Definition of Electric Current

Before we get to know electric current, let’s take a moment back to get to know the constituents of any material that exists on this earth.

Every material is composed of atoms. Atoms have 3 smallest parts called protons, electrons and neutrons.

Protons are the parts of the atom that have a positive charge.

Electrons are the parts of the atom that have a negative charge.

Neutrons are the uncharged (neutral) parts of the atom.

An atom can be modeled by a sphere that has a trajectory. This modeling is known as the Bohr atomic model.

Bohr’s Atomic Model (source: batan)

Protons and neutrons are at the midpoint (nucleus), while electrons are in a trajectory (orbit).

If the number of protons and electrons in an atom is the same, then the atom is said to be uncharged or neutral.

If there are more protons than electrons, then the atom is said to be positively charged.

If the number of electrons is more than protons, then the atom is said to be negatively charged.

The electrons that are in the outermost path, will be released if energy is given to them.

If these electrons are released from their trajectory, they are said to be free electrons. It will leave a space inside the atom. This space is called a hole.

Free electrons, can move anywhere.

If a material has a lot of free electrons, then we call it “Electric Charge”. More specifically, it says “Negative Electric Charge”.

If this electric charge moves from one area to another, it is called Electric Current.

So, electric current is an electric charge that moves from one point to another in 1 second.

One point here is not “dots”, it means it can be from one end of the cable to the other or from the electrical circuit to another.

### Number of Electrons in 1 Ampere?

Now, let’s take a deeper look. If electrons are moving in the current, how many electrons are moving?

The unit used in current is the Ampere. It denoted by “I”.

1 Ampere is 1 Coulomb per Second (1 A = 1 C / s).

1 Coulomb is a unit of electric charge consisting of 6,250,000,000,000,000,000 free electrons.

So, 1 Ampere is 6,250,000,000,000,000,000 grains of free electrons moving from one point to another in 1 second.

1 electron has a charge of 1.602×10-19 C.

Why Can Current Flow?

After we know that the current is actually a moving electron, then what is the reason why these electrons can move in a conductor such as a cable, for example?

To be able to move the electrons, the condition is that there is a potential difference between the 2 points.

For more details, please read the Explanation of Electric Voltage, Units and Formulas.