物理与光电工程学院：《大学物理》课程PPT教学课件（讲稿，英文第三版）Chapter 27 Electromagnetic Induction and Faraday's Law

Chapter 27 Electromagnetic Induction and Faradays Law Chapter 27 Electro-Magnetic Induction and faraday's Law 1. The Law of Electro-Magnetic Induction 2. Motional induced emf

Chapter 27 Electromagnetic Induction and Faraday’s Law Chapter 27 Electro-Magnetic Induction and Faraday’s Law 1. The Law of Electro-Magnetic Induction 2. Motional & Induced Emf

Chapter 27 Electromagnetic Induction and faraday's law New words and Expressions magnetic flux 磁通量 electromagnetic induction 电磁感应 induced current 感应电流 electromotive force(emf) 电动势 induced emf 感应电动势 magnetic flux linkage 磁通链 motion electromotive force 动生电动势

Chapter 27 Electromagnetic Induction and Faraday’s Law New words and Expressions magnetic flux 磁通量 electromagnetic induction 电磁感应 induced current 感应电流 electromotive force (emf) 电动势 induced emf 感应电动势 magnetic flux linkage 磁通链 motion electromotive force 动生电动势

Chapter 27 Electromagnetic Induction and faraday's law Introduction After Oersteds discovery in 1820: a steady current produced a steady magnetic field, experimentalists eagerly sought to demonstrate the reverse: a steady magnetic field could create a steady electric current. 1820年丹麦物理学家奥斯特发现了电流的磁效应, 就开始了其逆效应的研究

Chapter 27 Electromagnetic Induction and Faraday’s Law After Oersted’s discovery in 1820: a steady current produced a steady magnetic field, experimentalists eagerly sought to demonstrate the reverse: a steady magnetic field could create a steady electric current. 1820年丹麦物理学家奥斯特发现了电流的磁效应， 就开始了其逆效应的研究。 Introduction

Chapter 27 Electromagnetic Induction and faraday's law Michael Faraday, English physicist and chemist, whose experiments covered a wide range of electrical, magnetic, optical and chemical phenomena. He is best known for his discovery of electro-magnetic induction 2清 1831年8月英国物理学家 M. Faraday发现了电磁感应定律。大 大推动了电磁理论的发展。 电磁感应定律的发现,不但找到了磁生电的规律, 更重要的是它揭示了电和磁的联系,为电磁理论奠定了 基础。并且开辟了人类使用电能的道路。成为电磁理论 发展的第一个重要的里程碑

Chapter 27 Electromagnetic Induction and Faraday’s Law 电磁感应定律的发现，不但找到了磁生电的规律， 更重要的是它揭示了电和磁的联系，为电磁理论奠定了 基础。并且开辟了人类使用电能的道路。成为电磁理论 发展的第一个重要的里程碑。 1831 年 8 月 英 国 物 理 学 家 M.Faraday发现了电磁感应定律。大 大推动了电磁理论的发展。 Michael Faraday, English physicist and chemist, whose experiments covered a wide range of electrical, magnetic, optical and chemical phenomena. He is best known for his discovery of electro-magnetic induction

Chapter 27 Electromagnetic Induction and faraday's law 27-1. Induced EMF page629-630 1. Two experiments First experiment D)A current appears only if there is relative motion between the loop and the magnet; the current disappears when the relative motion between them ceases 导体回路和磁铁有相对运动时,回路中就会产生电流

Chapter 27 Electromagnetic Induction and Faraday’s Law 27-1. Induced EMF page629-630 1. Two experiments I N First experiment S 1) A current appears only if there is relative motion between the loop and the magnet; the current disappears when the relative motion between them ceases. 导体回路和磁铁有相对运动时, 回路中就会产生电流

Chapter 27 Electromagnetic Induction and faraday's law 2)Faster motion produces a greater current. 3)The opposite moving direction causes an opposite current.(如果磁铁的运动方向相反,则产 生的电流方向相反) Magnet moves up Magnet toward moves down

Chapter 27 Electromagnetic Induction and Faraday’s Law 2) Faster motion produces a greater current. 3) The opposite moving direction causes an opposite current. (如果磁铁的运动方向相反, 则产 生的电流方向相反)

Chapter 27 Electromagnetic Induction and Faradays Law B变一→￠变 S变变

Chapter 27 Electromagnetic Induction and Faraday’s Law B变  变 S变  变

Chapter 27 Electromagnetic Induction and faraday's law Second experiment If we close(or open) switch to turn on a current in the right-hand loop, the meter suddenly and briefly registers a current in the left-hand loop Galvanometer Iron Switch Battery

Chapter 27 Electromagnetic Induction and Faraday’s Law Second experiment If we close (or open) switch to turn on a current in the right-hand loop, the meter suddenly and briefly registers a current in the left-hand loop

Chapter 27 Electromagnetic Induction and Faradays Law STTTTTTTTTTD> 0 L闭合电键‖L断开电鍵 变B变=变

Chapter 27 Electromagnetic Induction and Faraday’s Law I变 B变  变

Chapter 27 Electromagnetic Induction and faraday's law 2. Electromagnetic induction 分析上述几个实验,尽管在闭合回路中引起电流的 方式有所不同,但产生电流这一现象的共同原因是:当 穿过一个闭合导体回路所限定的面积的磁通Φ随时间发 生了变化。 1)电磁感应现象一穿过一个闭合回路的磁通量发生变 化时在回路中产生电流的现象 Electromagnetic induction: The process of producing the current and emf is called induction

Chapter 27 Electromagnetic Induction and Faraday’s Law 分析上述几个实验，尽管在闭合回路中引起电流的 方式有所不同，但产生电流这一现象的共同原因是：当 穿过一个闭合导体回路所限定的面积的磁通Φ随时间发 生了变化。 1) 电磁感应现象--穿过一个闭合回路的磁通量发生变 化时在回路中产生电流的现象. Electromagnetic induction: The process of producing the current and emf is called induction. 2. Electromagnetic induction