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Chapter 26

Current and Resistance

Courant électrique
Courant électrique
Electrical current is defined as the rate at which charge flows. When there is a large current present, such as that used to run a refrigerator, a large ...
Vitesse de dérive
Vitesse de dérive
The high speed of electrical signals results from the fact that the force between charges acts rapidly at a distance. Thus, when a free charge is forced ...
Densité de courant
Densité de courant
The total amount of current flowing through one unit value of a cross-sectional area is referred to as current density. If the current flow is uniform, ...
Résistivité
Résistivité
When a voltage is applied to a conductor, an electrical field is generated, and charges in the conductor feel the force due to the electrical field. The ...
Résistance
Résistance
When a current moves through any conductor, the conductor causes some level of difficulty for the current to flow. The measure of that difficulty is known ...
Loi d’Ohm
Loi d’Ohm
Many materials exhibit a simple relationship between the values of current, voltage, and resistance, known as Ohm’s law. The current that flows ...
Dispositifs non ohmiques
Dispositifs non ohmiques
In most substances, the current flow is proportional to the voltage applied to it. A simple relationship between the values of current, voltage, and ...
Alimentation électrique
Alimentation électrique
Electric power is the product of current and voltage, represented in units of joules per second, or watts. For example, cars often have one or more ...
Énergie électrique
Énergie électrique
Using electric appliances for a longer period of time consumes more electrical energy and results in a higher electric bill. The energy produced by the ...
Équation de continuité
Équation de continuité
The total amount of current flowing per unit cross-sectional area is called the current density. Hence, the current passing through a cross-sectional area ...
Conditions aux limites de la densité de courant
Conditions aux limites de la densité de courant
Current density becomes discontinuous across an interface of materials with different electrical conductivities. The normal component of the current ...
Conductivité électrique
Conductivité électrique
In perfect conductors, the electric field inside is always zero due to the abundance of free electrons, which nullify any field by flowing. As a result, ...
Théorie de la conduction métallique
Théorie de la conduction métallique
The conduction of free electrons inside a conductor is best described by quantum mechanics. However, a classical model makes predictions close to the ...
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