04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
Faraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} Gen 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoanerators and Motors31.6(Optional} Eddy Currents31.7Maxwell's Wonderful Equations979980CHAPĨÍR ỉi Faraday’s Law?■ he focus of our studies in electricity and magnetism so far has been the electric fields produced by stationary charges and the magnetic fields produced by moving charges. This chapter de 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoaals with electric fields produced by changing magnetic fields.Experiments conducted by Michael Faraday in England in 1831 and independently by Joseph04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
Henry in the United States that same year showed that an eml can be- induced in a circuit by a changing magnetic field. As we shall see, an emf (and tFaraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} Gen 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa results of these experiments led to a very basic and important law of elec tromagnetism known as laraday's law of induction. This law states that the magnitude of the emf induced in a circuit equals the time rate of change of the magnetic flux through the circuit.With the treatment of Faraday's law 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa, we complete our introduction to the fundamental laws of electromagnetism. These laws can be- summarized in a set of four equations called Maxwell's04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
equations. Together with the hnrnlz force law. which we discuss briefly, they represent a complete theory for describing the interaction of charged obFaraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} Gen 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoaW OF INDUCTION"Ộ' To sec how an cmf can lx? induced by a changing magnetic field, let US consider a «■* loop of wire connected to a galvanometer, as illustrated in Figure 31.1. When a 1*7 magnet is moved toward the loop, the galvanometer needle deflects in one direction. arbitrarily shown to the rig 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoaht in Figure 31.1a. When the magnet is movedA demonstration of electromagnetic induction. A changing potential difference is applied to the lower coil04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
. .An cmf is induced in the upper coil as indicated by the illuminated lamp What happens to the lamp's intensity as the upper coil is moved over the vFaraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} Gen 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoaagnet is held stationary relative to the loop (Fig. 31.1b), no deflection is observed. Finally, if the magnet is held staũonary and the loop is moved cither toward or away from it. the needle deflects. From these observations, we conclude that the loop -knows" that the magnet is moving relative to i 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoat because it experiences a change in magnetic field. Thus, it seems that a relationship exists between current and changing magnetic field.These resul04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
ts arc quite remarkable in view of the fact that a current is set up even though no batteries are present in the circuit! We call such a current an inFaraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} Gen 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoaprimary coil is connected to a switch and a battery. The coil is wrapped around a ring, and a current in the coil produces a magnetic field when the switch is closed. A secondary coil also is wrapped around the ring and is connected to a galvanometer. No battery is present in the secondary circuit, 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoaand the secondary coil is not connected to the primary coil. Any current delected in the secondary circuit must be induced by some external agent.Init04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
ially, you might guess that no current is ever detected in the secondary circuit. However, something quite amazing happens when the switch in the primFaraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} Gen 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoahl* galvanometer, he placed the meter in an adjacent room. Thus, as he moved the magnet in the l«K>p. he could not see the meter needle deflecting. By the lime he returned next door IO read the galvanometer. the needle- was back to zero because he had stopped moving the magnet. Unfortunately for Col 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoaladon. there must be relative motion between the loop and the magnet lor an induced cmf and a corresponding induced current to be observed. Thus, phys04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
ics students learn Faraday's law of induction rather than "Colladon's law of induction.*31.1 Foraday’s Lan of Induction981lb)Figure 31.1 (a) When a maFaraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} Gen 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoap, (b) When the magnet is held stationaiy. there is no induced current in the loop, even when the magnet is inside the loop, (c) When the magnet is moved away from the loop, the galvanometer deflects in the opposite direction, indicating that the induced CUI lent is opposite that shown in pan (a).(C 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoahanging the direction of thr magnet’s motion changes the direction of the current induced by that motion.circuit is either suddenly closed or suddenly04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
opened. Al the instant the switch is closed, the galvanometer needle deflects in one direction and then returns to zero. At the instant the switch isFaraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} Gen 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoaurrent or no current in the primary circuit. The key to under*Figure 31.2 faraday's experiment. When the switch in the primary circuit is closed, the galvanometer ill the secondary circuit deflects momentarily. The cmf induced ill die secondary cir-cuit is caused by die changing magnetic field lluou 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoagh the secondary coil.Michael Faraday <1791-1867)Faraday, a British physicist and chemist is often regarded as the greatest experimental scientist of04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoa
the 1800s. Ills many cnnlrilxilions Io Ihii sillily al electricity include the inven linn III the electric motor. dcclric generator, and Iranslomier, Faraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} Gen 04) electromagnetic induction (resnick halliday walker) kho tài liệu bách khoavelopment ol poison gas for the British military. /SrAiiKf ptmsstn 0< the f’rer.-dint end Council’ of the ílcyỉ! Society!Faraday’s Lawchapter31Chapter Outline31.1Faraday's Law of Induction31.2Motional emf31.3Lenz's Law31.4Induced emf and Electric Fields31.5(Optional} GenGọi ngay
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