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184_notes:magnetic_field [2017/11/30 05:53] – [The Magnetic Field] pwirving | 184_notes:magnetic_field [2021/07/06 17:30] – bartonmo | ||
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Chapters 17 and 20 of Matter and Interactions (4th edition) | Chapters 17 and 20 of Matter and Interactions (4th edition) | ||
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===== The Magnetic Field ===== | ===== The Magnetic Field ===== | ||
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{{youtube> | {{youtube> | ||
- | ==== Model of a moving point charge ==== | + | ===== Model of a moving point charge ===== |
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Our introduction to the magnetic field started with [[184_notes: | Our introduction to the magnetic field started with [[184_notes: | ||
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where the vector $\vec{r}$ is still the separation vector between the location of the moving charge at a given time and the observation location at the same time -- assuming that the charge is moving much more slowly than the speed of light. Again, we cannot derive this equation, it is a model of the point charge magnetic field that fits the data/ | where the vector $\vec{r}$ is still the separation vector between the location of the moving charge at a given time and the observation location at the same time -- assuming that the charge is moving much more slowly than the speed of light. Again, we cannot derive this equation, it is a model of the point charge magnetic field that fits the data/ | ||
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If another moving charge is brought into the scene, it will interact with the first moving charge through the magnetic field that the first charge generates. (It will also experience the electric force, but we often limit our discussion at first to the isolated magnetic interaction.) This push or pull that the new moving charge experiences is directly related to the cross product of the velocity of that charge and the magnetic field of the source charge. This [[184_notes: | If another moving charge is brought into the scene, it will interact with the first moving charge through the magnetic field that the first charge generates. (It will also experience the electric force, but we often limit our discussion at first to the isolated magnetic interaction.) This push or pull that the new moving charge experiences is directly related to the cross product of the velocity of that charge and the magnetic field of the source charge. This [[184_notes: | ||
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==== Collections of moving charges ==== | ==== Collections of moving charges ==== | ||
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A single moving charge is certainly not the only kind of situation that we encounter. In fact, it's quite often that a collection of charges are moving -- forming a current. This collection of moving charges or really [[184_notes: | A single moving charge is certainly not the only kind of situation that we encounter. In fact, it's quite often that a collection of charges are moving -- forming a current. This collection of moving charges or really [[184_notes: | ||
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==== Effects and Applications ==== | ==== Effects and Applications ==== | ||
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The fact that moving charges generate magnetic fields, that they superpose, and that other moving charges experience magnetic forces in the presence of a magnetic field result in a number of different magnetic phenomenon. Some are quite practical. Some of the most important ones are discussed below: | The fact that moving charges generate magnetic fields, that they superpose, and that other moving charges experience magnetic forces in the presence of a magnetic field result in a number of different magnetic phenomenon. Some are quite practical. Some of the most important ones are discussed below: | ||
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=== Current-carrying wires === | === Current-carrying wires === | ||
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=== Curved motion === | === Curved motion === | ||
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Magnetic fields [[184_notes: | Magnetic fields [[184_notes: | ||