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Chapter 29

Sources of Magnetic Fields

移动电荷引起的磁场
移动电荷引起的磁场
A stationary charge creates and interacts with the electric field, while a moving charge creates a magnetic field. Consider a point charge moving with a ...
Biot-Savart 定律
Biot-Savart 定律
The Biot-Savart law gives the magnitude and direction of the magnetic field produced by a current. This empirical law was named in honor of two ...
Biot-Savart 定律:解决问题
Biot-Savart 定律:解决问题
The magnitude and direction of a magnetic field created by a steady current can be calculated using the Biot-Savart law. Consider a mobile phone battery ...
细直线产生的磁场
细直线产生的磁场
Consider an infinitely long straight wire carrying a current I. The magnetic field at point P at a distance a from the origin can be calculated using the ...
两条直线产生的磁场
两条直线产生的磁场
Consider two parallel straight wires carrying a current of 10 A and 20 A in the same direction and separated by a distance of 20 cm. Calculate the ...
两个并联电流之间的磁力
两个并联电流之间的磁力
Two long, straight, and parallel current-carrying conductors exert a force of equal magnitude on one another. The direction of the force depends on the ...
电流回路的磁场
电流回路的磁场
Consider a circular loop with a radius a, that carries a current I. The magnetic field due to the current at an arbitrary point P along the axis of the ...
磁场的发散和卷曲
磁场的发散和卷曲
The magnetic field due to a volume current distribution given by the Biot–Savart Law can be expressed as follows: To evaluate the divergence of the ...
安培定律
安培定律
A fundamental property of a static magnetic field is that it is not conservative, unlike an electrostatic field. Instead, there is a relationship between ...
安培定律:解决问题
安培定律:解决问题
Ampere's law states that for any closed looped path, the line integral of the magnetic field along the path equals the vacuum permeability times the ...
螺线管
螺线管
A solenoid is a conducting wire coated with an insulating material, wound tightly in the form of a helical coil. The magnetic field for a solenoid is the ...
螺线管的磁场
螺线管的磁场
A solenoid is a conducting wire coated with an insulating material, wound tightly in the form of a helical coil. The magnetic field due to a solenoid is ...
环形线圈
环形线圈
A toroid is a closely wound donut-shaped coil constructed using a single  conducting wire. In general, it is assumed that a toriod consists of ...
磁矢量电位
磁矢量电位
In electrostatics, the electric field can be written as the negative gradient of the potential. In magnetostatics, the zero divergence of the magnetic ...
磁化物体引起的电位
磁化物体引起的电位
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs ...
静磁边界条件
静磁边界条件
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular ...
物质中的安培定律
物质中的安培定律
The total current density in magnetized material is the sum of the free and bound current densities. The free current arises due to the motion of free ...
磁化率和磁导率
磁化率和磁导率
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of ...
电子的磁矩
电子的磁矩
Electrons revolving around a nucleus are analogous to a circular current carrying loop. This current produces a magnetic dipole moment proportional to the ...
反磁性
反磁性
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the ...
顺磁性
顺磁性
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly ...
铁磁性
铁磁性
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic ...
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