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Chapter 26

Current and Resistance

电流
电流
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 ...
漂移速度
漂移速度
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 ...
电流密度
电流密度
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, ...
电阻 率
电阻 率
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 ...
电阻
电阻
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 ...
欧姆定律
欧姆定律
Many materials exhibit a simple relationship between the values of current, voltage, and resistance, known as Ohm’s law. The current that flows ...
非欧姆器件
非欧姆器件
In most substances, the current flow is proportional to the voltage applied to it. A simple relationship between the values of current, voltage, and ...
电力
电力
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 ...
电能
电能
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 ...
连续性方程
连续性方程
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 ...
电流密度的边界条件
电流密度的边界条件
Current density becomes discontinuous across an interface of materials with different electrical conductivities. The normal component of the current ...
电导率
电导率
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, ...
金属传导理论
金属传导理论
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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