Physics behind recorders ?

Discussion in 'Physics & Math' started by Challenger78, Jul 31, 2009.

  1. Challenger78 Valued Senior Member

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    If Magnets are involved in producing sound, whats the physics in recording them ?

    Do The compressions and rarefactions vibrate an object/coil that causes a changing mangnetic field which then records it onto tape ?
     
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  3. temur man of no words Registered Senior Member

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    I think there are many ways. The one that you described, and piezo-electric stuff come to mind.
     
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  5. Pete It's not rocket surgery Registered Senior Member

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  7. Challenger78 Valued Senior Member

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    I should have googled it. My bad.
    Anywho,
    So the magnetic flux is recorded in the tape..

    "During playback, the motion of the tape pulls a varying magnetic field across the gap. This creates a varying magnetic field in the core and therefore a signal in the coil. This signal is amplified to drive the speakers. "

    Is the tape generating a magnetic field ?, I thought it was inert ?
     
  8. Pete It's not rocket surgery Registered Senior Member

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    The tape is magnetized, like a permanent magnet. Or, more precisely, the tape contains thousands of tiny permanent magnets that were previously magnetised during recording.
    Pulling the tape past the tape head means pulling each tiny magnet past the head. Since the magnets don't all have the same strength, the magnetic field across the gap varies up and down, as stronger and weaker magnets go past.
     
  9. Challenger78 Valued Senior Member

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    Which then induces a current in a circuit somewhere, which becomes amplfied into the speakers, and what not...

    Cool..

    This makes physics somewhat more bearable.
     

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