Fundamentals of Physics 8/e 30 - Inductance D. Halliday, R. Resnick, and J. Walker 國立彰化師大教學卓越計畫 理學院普通物理整合型教材 主持人：郭艷光院長

彰化師大教學卓越－普物教材－理學院長郭艷光主持 Outline 30-1 What Is Physics? 30-2 Two Experiments 30-3 Faraday’s Law of Induction 30-4 Lenz’s Law 30-5 Induction and Energy Transfers 30-6 Induced Electric Fields 30-7 Inductors and Inductance 30-8 Self-Induction 30-9 RL Circuits 30-10 Energy Stored in a Magnetic Field 30-11 Energy Density of a Magnetic Field 30-12 Mutual Induction 彰化師大教學卓越－普物教材－理學院長郭艷光主持

彰化師大教學卓越－普物教材－理學院長郭艷光主持 30-1 What Is Physics? In Chapter 29 we discussed the fact that a current produces a magnetic field. That fact came as a surprise to the scientists who discovered the effect. Perhaps even more surprising was the discovery of the reverse effect: A magnetic field can produce an electric field that can drive a current. This link between a magnetic field and the electric field it produces (induces) is now called Faraday’s law of induction. 彰化師大教學卓越－普物教材－理學院長郭艷光主持

彰化師大教學卓越－普物教材－理學院長郭艷光主持 30-2 Two Experiments A current appears only if there is relative motion between the magnet and the loop. Faster motion results in a larger current. If we reverse the direction of motion or the polarity of the magnet, the current reverses sign and flows in the opposite direction. The current generated is known as “induced current”; the emf that appears is known as “induced emf”; the whole effect is called “induction”. loop 1 loop 2 彰化師大教學卓越－普物教材－理學院長郭艷光主持

30-3 Faraday’s Law of Induction Magnetic Flux ФB SI magnetic flux unit: T‧m² known as the Weber (symbol Wb) 彰化師大教學卓越－普物教材－理學院長郭艷光主持

彰化師大教學卓越－普物教材－理學院長郭艷光主持 30-4 Lenz’s Law 1. Opposition to pole movement 彰化師大教學卓越－普物教材－理學院長郭艷光主持

彰化師大教學卓越－普物教材－理學院長郭艷光主持 30-4 Lenz’s Law 2. Opposition to flux change 彰化師大教學卓越－普物教材－理學院長郭艷光主持

30-5 Induction and Energy Transfers 彰化師大教學卓越－普物教材－理學院長郭艷光主持

30-5 Induction and Energy Transfers Eddy currents 彰化師大教學卓越－普物教材－理學院長郭艷光主持

30-6 Induced Electric Fields 彰化師大教學卓越－普物教材－理學院長郭艷光主持

30-7 Inductors and Inductance 彰化師大教學卓越－普物教材－理學院長郭艷光主持

彰化師大教學卓越－普物教材－理學院長郭艷光主持 30-8 Self-Induction loop 1 loop 2 彰化師大教學卓越－普物教材－理學院長郭艷光主持

彰化師大教學卓越－普物教材－理學院長郭艷光主持 30-9 RL Circuits 彰化師大教學卓越－普物教材－理學院長郭艷光主持

30-10 Energy Stored in a Magnetic Field 彰化師大教學卓越－普物教材－理學院長郭艷光主持

30-11 Energy Density of a Magnetic Field 彰化師大教學卓越－普物教材－理學院長郭艷光主持

彰化師大教學卓越－普物教材－理學院長郭艷光主持 30-12 Mutual Induction The SI unit for M: the Henry (H) 彰化師大教學卓越－普物教材－理學院長郭艷光主持

彰化師大教學卓越－普物教材－理學院長郭艷光主持 End of chapter 30! 彰化師大教學卓越－普物教材－理學院長郭艷光主持