# Electric Current

Edited by Simo, SmartyPants, Sharingknowledge, Jen Moreau and 1 other

We use electricity every day, sometimes without even realizing it. Electricity enables us to use our laptops, phones, TV's, to light our homes, heat our pools, wash our clothes and dry our hair. The flow of energy from power plants into our homes and throughout our communities occurs through a utility grid.

Electric current is defined as the movement of electrons inside conductors and between two points of a circuit. To understand this concept, an understanding of the Atom is necessary.

## Atoms: Structure

1. 1
Atoms are the smallest particles of matter
.
Every solid, liquid, gas and plasma is composed of atoms. The atom itself is composed of a nucleus (protons and neutrons) and electrons. The electrons orbit the nucleus of the atom, the same way the planets in our solar system orbit the sun. The proton (positively charged) keep the electrons (negatively charged) in orbit. The number of electrons and protons define the element of the atom. For example, Hydrogen atoms have one electron and one proton.
2. 2
Multiple electrons can orbit the nucleus
.
For example, the bore atom has five protons and five electrons orbiting while the copper atom has 29 protons and 29 electrons orbiting. When there are multiple electrons orbiting, the electrons orbit in different layers. The electrons orbiting the nucleus in the closer layer are termed bound electrons and are very difficult separate from the atom. The electrons in the outer layers are easier to separate from the atom and are termed free electrons.
3. 3
When an atom loses free electrons, the number of protons (positive charges) increases, and outnumber the electrons (negative charge)
.
Because there are more protons than electrons, the atom becomes positively charged. In the same way, if we introduce free electrons into another atom's layer it becomes negatively charged.
4. 4
An electric charge is defined as Q and its unit is the Coulombs (C)
5. 5
An electron has an electric charge of -1,602Q - 10-19 C
.

## Electric Current

1. 1
A basic principle of electrostatics states when two charged particles have the same charge they repel each other but if two charged particles have different charges they will attract one another
.
A common battery has a positive (+) pole (atoms in this pole are positively charged, they have a bigger number of protons compared to electrons), and a negative (-) pole (atoms in that pole are negatively charged, and have a smaller number of protons compared to electrons). When a conductor is placed between the two poles (copper wire for example), the free electrons within the conductor's atom will start moving toward the positively charged pole, creating an electric current.
2. 2
An electric current is measured using an ampere-meter and its unit is the Ampere (A)
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1A is equivalent to 6 250 000 000 000 000 000 electrons moving from the negative pole to positive pole within 1s.
3. 3
To express the previous relationship between the current and the charged particles, a mathematical equation can be driven as: ?Q=I ?t Where ?Q is the charge in Coulombs (C) flowing between two points of electric circuits, I is the current measured, finally, ?t is time needed in seconds (s).
4. 4
Like all other units, Ampere has a conversion table as shown below
.

## Electric Voltage

1. 1
The voltage is the difference of electric potential (difference in charged atoms) between two points in an electric circuit such as the two poles of a battery
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The point with the highest potential will repel electrons toward the point with the lowest potential, exactly like water flowing down from the highest point in a waterfall to the lowest point.
2. 2
Voltage can be compared to altitude and the current can be compared to the flow of water
.
The voltage expresses the electron unbalance existing between the poles as volts (V) and measured using a voltmeter. The conversion table of the volt is given below.
3. 3
The voltage between two points in a circuit and the current flowing between these two points represents the electric power (expressed in watt (W)), The mathematical equation that links these parameters is defined by
:
P=I.V Where P is expressed in watt, V is the voltage in volts and I is the current expressed in amperes.

## Ohm's Law

1. 1
There is a direct relation between the voltage and current termed Ohm's law.
2. 2
Ohm's law states that there is a linear relationship between the voltage and the current in an electrical circuit
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Expressed as a mathematical formula: V=I*R
3. 3
Where V is the voltage between two points in an electric circuit, I is the current flowing between the two points, and finally, R is the resistance of the material
.
The resistance expresses the ability of the material to oppose the flow of electrons.

## Example

1. 1
To understand the previous equation, an electric circuit is shown in Figure 5
.
Using a 12V battery supply the objective is to determine the value of the resistance using experimental measurements.
2. 2
The voltage of the battery is 12.24 as shown in the picture; a voltmeter has been used to measure the voltage
.
3. 3
Once the LED is supplied an electric current will flow from the positive pole of the battery through the circuit then returning to the battery, the measurement of the current give 29.71 mA
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As shown in the picture below.
4. 4
Theoretically, we can predict the value of the resistance applying the equation
:
R=V/I=12.24/29.71=411 ?

APA (American Psychological Association)
Electric Current. (2017). In ScienceAid. Retrieved Sep 24, 2023, from https://scienceaid.net/electric_current

MLA (Modern Language Association) "Electric Current." ScienceAid, scienceaid.net/electric_current Accessed 24 Sep 2023.

Chicago / Turabian ScienceAid.net. "Electric Current." Accessed Sep 24, 2023. https://scienceaid.net/electric_current.

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## Article Info

Categories : Physics

Recent edits by: Jen Moreau, Sharingknowledge, SmartyPants