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Chapter 26

Current and Resistance

Электрический ток
Электрический ток
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 ...
Скорость дрейфа
Скорость дрейфа
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 ...
Плотность тока
Плотность тока
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, ...
Удельное сопротивление
Удельное сопротивление
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 ...
Сопротивление
Сопротивление
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 ...
Закон Ома
Закон Ома
Many materials exhibit a simple relationship between the values of current, voltage, and resistance, known as Ohm’s law. The current that flows ...
Неомические устройства
Неомические устройства
In most substances, the current flow is proportional to the voltage applied to it. A simple relationship between the values of current, voltage, and ...
Электроэнергии
Электроэнергии
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 ...
Электроэнергия
Электроэнергия
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 ...
Уравнение непрерывности
Уравнение непрерывности
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 ...
Граничные условия для плотности тока
Граничные условия для плотности тока
Current density becomes discontinuous across an interface of materials with different electrical conductivities. The normal component of the current ...
Электропроводность
Электропроводность
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, ...
Теория металлической проводимости
Теория металлической проводимости
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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