Electricity is the movement of electric charges that circulate through a conductor. This movement takes place in accordance with certain physical properties. These properties are contained in a series of laws and theorems that scientists have developed throughout history.
The most important laws and theorems related to electrical energy are:
Coulomb's law
Coulomb's law states that the electric force on two charged objects is inversely proportional to the square of the distance between them. Coulomb's law also states that this force is directly proportional to the product of the charges.
This law was first introduced in 1785 by the physicist Charles-Augustin de Coulomb .
Ampere's law
Ampere's law was developed by the Frenchman André-Marie Ampère in 1831. Ampere's law relates a static magnetic field to its cause. It was later corrected by James Clerk Maxwell and became part of Maxwell's equations.
Ampere's law indicates that the circulation of the magnetic field intensity in a closed contour is proportional to the electric current that flows in that contour.
Ohm's law
Ohm's law states that the intensity of electric current flowing through a conductor connecting two points is directly proportional to the voltage between the two points and inversely proportional to the electrical resistance of the conductor.
Ohm's law describes with great precision the behavior of almost all electrically conductive materials. However, there are some conductive materials that do not follow this law. These are called non-ohmic conductive materials.
The law is named after the German physicist George Ohm. In 1827, George Ohm described the currents and voltages that occurred in simple electrical circuits. In his honour, resistance is expressed in Ohms (ω).
Faraday's law
Faraday's law of electromagnetic induction is a basic law of electromagnetism, with:
- a transformer
- an inductance element
- a plurality of generator operation close up.
The law states that: " The magnitude of the electromotive force induced in any closed circuit is equal to the rate of change of the magnetic flux through the circuit."
This law was discovered by Michael Faraday in 1831. Joseph Henry discovered this law before Faraday in an independent study in 1830, but he did not publish this discovery. Therefore, this law is called Faraday's law.
Traditionally, there are two ways to change the magnetic flux through the circuit. As for induced electromotive force, what changes is its own electric field, such as changing the current that generates the field (like a transformer). As for electromotive driving force, what changes is the movement of all or part of the circuit in the magnetic field, such as in a generator of the same polarity.
Kirchhoff's electrical laws
These laws are composed of two fundamental principles that we explain below:
Kirchhoff's current law (node law)
Kirchhoff's current law, also known as the node law , is based on the conservation of electric charge. When we consider a node in an electrical circuit, this is a point where several conductors are connected.
According to this law, the sum of the currents entering a node must equal the sum of the currents leaving that node. In other words, there can be no charge accumulation at the node; charge entering must leave.
This electrical rule is expressed mathematically as follows:
I input = I output
This means that if you have several currents flowing into a node, and several currents flowing out of it, the total sum of the currents entering minus the total sum of the currents leaving is equal to zero.
If you add up all the currents coming in and going out, the total must be zero.
Kirchhoff's stress law (mesh law)
Kirchhoff's voltage law, or mesh law , is based on the conservation of energy in a circuit.
This electrical law states that if you draw a closed path (or mesh) in a circuit, the sum of all the voltage drops along that path must equal the sum of the voltages (energy sources) in the same path.
Specifically, the law says that:
- When you pass through a component that consumes power (such as a resistor), the voltage drop is counted as negative.
- When you pass through a voltage source (like a battery), the voltage is counted as positive.
So if we add up all the tensions in a closed path, we get zero:
V sources = V falls
This principle implies that the total energy supplied in the circuit is equal to the energy consumed.
It's like you're traveling along a route: if you start and end at the same place (like on a mesh), the total altitudes (tensions) you go up must equal the total you go down.
Gauss's law
Gauss's Law is a principle in electromagnetism that describes how the electric flux through a closed surface is related to the amount of electric charge within that surface.
In simple terms, this law states that if you imagine a sphere or any closed shape around an electric charge, the total electric flux leaving that surface is directly proportional to the charge that is enclosed within it.
The idea behind this electrical law is that the electric flux represents how many electric field lines pass through the surface. If there is more charge inside the surface, there will be more field lines coming out of it. This principle applies regardless of the shape of the surface, as long as it remains closed.