Lenz's law

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an induced current always flows to oppose the changewhich startrd it in a magnetic field.

紅字果句唔明 -  - "
其實姐係點 ..
個induced current oppose 個magnetic field ?

orb

假設一個磁鐵要穿過一個銅線圈

相對於銅線圈, magnetic field有變化

銅線圈內會有一current產生magnetic field去彈返舊磁鐵去原位

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呢題我唔知佢做緊d咩..都冇magnet,,我唔明個原理-0-

Ivanhy92

http://i554.photobucket.com/albums/jj423/cheukkan3b39/solenoid.jpg

呢題我唔知佢做緊d咩..都冇magnet,,我唔明個原理-0-
小霞的fans 發表於 6-12-2009 17:36

                               
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有Magnet...

當switch S開左就產生magnetic field

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when switch is closed,a magnetic field will be bulit up in the solenoid.
there will be an induced current flowing in the aluminium ring.By Lenz's law.the induced current flows in a direction such that it produces an effect to oppose the change.
so the end of the ring near the solenoid becomes a south pole.the aluminium ring will move away from the solenod under the action of the replusive force acting on it by the solenoid.

紅字果度開始唔明 . . 我唔明soft iron rod,aluminium ring同coil之間的關係..
current流經coil關aluminium ring咩事 .. 點解會有個induced current出左黎!?
理解唔到發生緊咩事..

希望有人詳細解釋比我聽..十萬個唔該><

orb

when switch is closed,a magnetic field will be bulit up in the solenoid.
so there is change of magnetic field along the solenoid
which also affect the aluminium ring
there will be an induced current flowing in the aluminium ring
due to repulsion which tends to change the magnetic field back to normal
By Lenz's law.the induced current flows in a direction such that it produces an effect to oppose the change.

so the end of the ring near the solenoid becomes a south pole.the aluminium ring will move away from the solenod under the action of the replusive force acting on it by the solenoid.