Electric current is the flow of electric charge through a conducting medium, such as a wire. When electrons flow through a conductor, they create a current that can be measured in amperes (A). The movement of electrons is caused by a difference in electrical potential between two points in a circuit, known as voltage.
When there is a transfer of charge from one side of an area to the other, we say that there is an electric current through the area. If the moving charges are positive, the current is in the direction of motion. If they are negative, the current is opposite to the direction of motion.
Thus, electric current through an area is the rate of transfer of charge from one side of the area to the other in conductors.
Voltage provides energy to electrons, allowing them to move through a circuit. This movement
of electrons is current, which results in work being done in an electrical circuit.
As you have learned, free electrons are available in all conductive and semiconductive materials.
These outer-shell electrons drift randomly in all directions, from atom to atom, within the structure of the material, as indicated in Figure.
These electrons are loosely bound to the positive metal ions in the material, but because of thermal energy, they are free to move about the crystalline structure of the metal.
If a voltage is placed across a conductive or semiconductive material, one end becomes positive and the other negative, as indicated in Figure. The repulsive force produced by the negative voltage at the left end causes the free electrons (negative charges) to move toward the right.
The attractive force produced by the positive voltage at the right end pulls the free electrons to the right. The result is a net movement of the free electrons from the negative end of the material to the positive end, as shown in Figure
The movement of these free electrons from the negative end of the material to the positive
end is the electrical current, symbolized by I.
Current in a conductive material is determined by the number of electrons (amount of
charge) that flow past a point in a unit of time.
I = Q/t
where I is current in amperes (A), Q is charge in coulombs (C), and l is time in seconds (s).
One ampere (1 A) is the amount of current that exists when a number of electrons
having a total charge of one coulomb (1 C) move through a given cross-sectional
area in one second (1 s).
There are two main types of electric current: direct current (DC) and alternating current (AC).
Electric current is essential for powering many of the devices that we use on a daily basis, from our smartphones and laptops to our household appliances.
However, electric current can pose hazards such as electrical shocks or electrocution if not handled properly.
It is important to follow electrical safety rules, such as turning off power sources before working on electrical equipment and avoiding contact with wet surfaces or metal objects.
Personal protective equipment (PPE), such as gloves, safety glasses, and insulated tools, can also provide additional protection.