The idea of resistance is linked to the opposition that exercises something or someone. In the context of electricity, the concept refers to the component of a circuit that hinders the advance of electric current, to the general lock that the circuit exerts on the passage of current and to the magnitude that, in ohms, measures this property.
It is important to bear in mind that all materials exert a certain resistance to the passage of electric current. This means that all substances are opposed, with greater or lesser success, to the circulation of the stream. Those materials that exert a very low electrical resistance are called drivers. Gold and aluminum, for example, are often used as conductors.
Elements with high electrical resistance are used in circuits as resistors. These are pieces that even receive the name of electrical resistance and that are located between two specific points of the circuit to resist the passage of current.
To create a resistor it is necessary to combine certain resistive elements, such as carbon, thanks to which it is possible to reduce the passage of electric current. The maximum value of power that a resistor is able to dissipate conditions its electric tension maximum (also known as potential difference, is a magnitude that gives a value to the difference that any two points have in electric potential).
Discovery of electrical resistance
The discovery of electrical resistance dates from the year 1827, and the person to whom it is attributed is Georg simon ohm, a mathematician and physical who lived in Germany until the middle of the 19th century.
As his name suggests, it was also he who proposed the Ohm’s law, one of the laws of electricity, which determines that the intensity of the current that passes through a given conductor is proportional to the potential difference between its two extremes.
Attenuation of current flow
The electrical resistance, in short, supposes a difficulty for the passage of current in an electrical circuit. The circulation of electrical charges, therefore, is attenuated or impeded by electrical resistance.
If the electrons they flow through a conductor with little electrical resistance, they will find no trouble moving forward. Instead, when they run into a significant electrical resistance, their flow is interrupted and the electrons begin to collide with each other and get out of order, producing hot.
Electrical resistance and resistivity
The formula to express and calculate the electrical resistance of a conductive wire is ρ * l / S, in which ρ (the Greek letter that reads rho) the resistivity of the material or the coefficient of proportionality, l is the measure of the cable along y S is the area of its cross section.
The previous paragraph mentions the concept of resistivity, which is defined as the electrical resistance of a given material. The Unit that is used to express it is rho and is calculated by measuring ohms per meter. Its formula involves multiplying resistance (calculated in ohms) by the ratio of cross section (in square meters) over length (in meters). Resistivity serves to provide a description of how a material behaves when faced with the passage of electrical current.
When the resistivity has a high value, the material it describes is not a good conductor, and vice versa. Metals generally have a variable resistivity, which increases as your temperature increases; the semiconductors (elements that can behave as an insulator or a conductor, depending on certain factors, such as pressure, magnetic or electric field and incident radiation), on the contrary, have a resistivity inversely proportional to temperature.