Chapter 28 Inductance and Electromagnetic Oscillations Chapter 28 Inductance and Electromagnetic Oscillations 1. Self and Mutual Induction 2. Energy Stored in a Magnetic Field
Chapter 28 Inductance and Electromagnetic Oscillations Chapter 28 Inductance and Electromagnetic Oscillations 1. Self and Mutual Induction 2. Energy Stored in a Magnetic Field
Chapter 28 Inductance and Electromagnetic Oscillations New words and expressions self induction 自感应 inductance 感应系数 mutual induction 互感应 Inductor 感应器,电感线圈
Chapter 28 Inductance and Electromagnetic Oscillations New words and expressions self induction 自感应 inductance 感应系数 mutual induction 互感应 Inductor 感应器, 电感线圈
Chapter 28 Inductance and Electromagnetic Oscillations 28-2 Self-Induction 1. SelfInduction(自感应)(P645-647 The process that an induced emf appear in any coil in which the current is changing is called self-induction(由于自己线路中的电流的变化而在自 己的线路中产生感应电流的现象一一自感现象) If we establish a current l in the coil, the magnetic flux linkage Na is proportional to 1, ∝ Define proportionality constant is L, y=LI
Chapter 28 Inductance and Electromagnetic Oscillations 28-2. Self-Induction The process that an induced emf appear in any coil in which the current is changing is called self-induction (由于自己线路中的电流的变化而在自 己的线路中产生感应电流的现象－－自感现象). 1. Self-Induction (自感应)(P645-647): If we establish a current I in the coil, the magnetic flux linkage N is proportional to I, I Define proportionality constant is L, = LI
Chapter 28 Inductance and Electromagnetic Oscillations Then the coefficient is defined as the self-Inductance NΦ L= A coil that has significant self- inductance l is called an inductor Its si unit: henry(亨利)=1H=1Tm2/A related to the geometry of the coils and magnetic medium.自感系数与线圈的大小、形状、 磁介质、线圈密度有关,而与线圈中电流无关
Chapter 28 Inductance and Electromagnetic Oscillations I N L = Then the coefficient L is defined as the Self-Inductance. A coil that has significant selfinductance L is called an inductor. It related to the geometry of the coils and magnetic medium. 自感系数与线圈的大小、形状、 磁介质、线圈密度有关，而与线圈中电流无关。 1 henry (亨利) = 1 H = 1T.m2 Its SI unit: /A
Chapter 28 Inductance and Electromagnetic Oscillations 2. Self-Induction EMe The emf appears in self-induction is called self- induced emf It obeys Faraday's law ofinduction d d(NΦ) dt dt Y=LI dⅠ fl is constant E;=-L dt The minus sign indicates that the self-induced emf has the orientation such that it opposes the change in 1
Chapter 28 Inductance and Electromagnetic Oscillations The emf appears in self-induction is called selfinduced emf. It obeys Faraday’s law of induction. The minus sign indicates that the self-induced emf has the orientation such that it opposes the change in I. 2. Self-Induction EMF t i N d d = − where = LI If L is constant t I i L d d = − t N d d( ) = − dt d = −