法拉第電磁感應(yīng)及應(yīng)用-英文教案

1、Chapter 5Electromagnetic Induction (Generation of a Voltage)How to induce an EMF誘發(fā)電動勢Faradays Law法拉第定律 Forces acting on a conductor導(dǎo)體Lenzs Law楞次定律Back Electromotive Force (emf)反電動勢 Magnetic field磁場Perpendicular movement垂直運動Induced voltage感應(yīng)電壓Oppose反對Faradays Law -法拉第定律When a conductor電導(dǎo)體 is moved運動w

2、ithin a magnetic磁場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電導(dǎo)體 A magnetic field磁場 Relative motion between the conductor and field議案SNHere a conductor lies between two magnetic poles. If the conductor is moved down

3、wards a voltage is induced感應(yīng)電壓(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垂直運動 between the conductor電導(dǎo)體 and the magnetic field磁場. Electric generators發(fā)電機 use conductors that move continuously連續(xù)動作 through the magnetic fieldUsing Flemings right hand rule can determine which way the current flows電流流Forced motionVoltage (emf) produced

5、 is proportional to the number of conductors in the field數(shù)額導(dǎo)體 (N)Voltage (emf) is proportional to the change in the amount of flux通量變化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