法拉第电磁感应及应用-英文教案

1、Chapter 5Electromagnetic Induction (Generation of a Voltage)How to induce an EMF诱发电动势Faradays Law法拉第定律 Forces acting on a conductor导体Lenzs Law楞次定律Back Electromotive Force (emf)反电动势 Magnetic field磁场Perpendicular movement垂直运动Induced voltage感应电压Oppose反对Faradays Law -法拉第定律When a conductor电导体 is moved运动w

2、ithin a magnetic磁场field, it will “cut” through the field and will have an e.m.f. induced in it. 3 factors required for this to happen: A conductor电导体 A magnetic field磁场 Relative motion between the conductor and field议案SNHere a conductor lies between two magnetic poles. If the conductor is moved down

3、wards a voltage is induced感应电压(Conventional current flow shown).Reversal of the movement or the magnetic field direction would result in reversal of the e.m.f. polarity. NOTE If the conductor is parallel to the magnetic field, it will not produce an e.m.f. when moved.E.M.F. is induced into the condu

4、ctor when there is a perpendicular movement垂直运动 between the conductor电导体 and the magnetic field磁场. Electric generators发电机 use conductors that move continuously连续动作 through the magnetic fieldUsing Flemings right hand rule can determine which way the current flows电流流Forced motionVoltage (emf) produced

5、 is proportional to the number of conductors in the field数额导体 (N)Voltage (emf) is proportional to the change in the amount of flux通量变化over a time period NVemfExample 1: A microphone with 10 turns receives a bump (0.2 seconds in duration) which changes the amount of flux over the coil from 0.4Wb to 0.5Wb. What is the voltage produced at the plug of the microphone?V0 . 5 0.20.4)-(0.5 10 NVExample 2:Calculate the e.m.f. induced in a coil of 2,000 turns whic