The element that generates a high electrical resistance is called a resistor.
The idea of resistance is linked to the opposition exerted by something or someone. In the context of electricity , the concept refers to the component of a circuit that hinders the advance of the electric current , to the general block that the circuit exerts on the passage of the current and to the magnitude that, in ohms , measures said property. .
It is important to keep in mind that all materials exert a certain resistance to the passage of electric current. This means that all substances oppose, with greater or lesser success, the circulation of the current . Those materials that exert a very low electrical resistance are called conductors . Gold and aluminum, for example, are often used as conductors.
The resistors
Elements that have a high electrical resistance are used in circuits as resistors . These are pieces that are even called electrical resistance and that are located between two specific points in 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 the flow of electric current is reduced. The maximum value of power that a resistor is capable of dissipating determines its maximum electrical voltage (also known as potential difference , it is a magnitude that gives a value to the difference that any two points have in electrical potential).
Discovery of electrical resistance
The discovery of electrical resistance dates back to 1827, and the person to whom it is attributed is Georg Simon Ohm , a mathematician and physicist who lived in Germany until the mid-19th century.
As his name suggests, it was also he who proposed Ohm's Law , one of the laws of electricity, which determines that the intensity of the current passing through a given conductor is proportional to the potential difference between its two ends. .
In a circuit, electrical resistance implies a difficulty for the passage of current.
Current flow attenuation
Electrical resistance, in short, represents 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 electrons flow through a conductor with low electrical resistance, they will have no problems moving forward. On the other hand, when they encounter significant electrical resistance, their flow is interrupted and the electrons begin to collide with each other and become disordered, producing heat .
Electrical resistance and resistivity
The formula to express and calculate the electrical resistance of a conductive cable is ρ * l / S , in which ρ (the Greek letter read rho ) the resistivity of the material or the coefficient of proportionality, l is the measurement of the cable a length and S is the surface of its cross section.
In the previous paragraph the concept of resistivity is mentioned, which is defined as the electrical resistance of a given material . The unit used to express it is rho and is calculated by measuring ohms per meter. Its formula involves multiplying the resistance (calculated in ohms) by the ratio of the cross section (in square meters) over the length (in meters). Resistivity serves to provide a description of the way 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. In general, metals have a variable resistivity, which increases as their temperature also increases ; 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 other hand, have a resistivity that is inversely proportional to temperature.