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Homework Help: Quick Question about the mag field of a solenoid

  1. Oct 24, 2004 #1
    A light bulb and a solenoid are connected in series to a battery. An iron rod is thrust rapidly into the solenoid and later rapidly removed. The bulb:

    1)No change in or out
    2)No change in, brightens out
    3)Dims in, Dims out
    4)Brightens in, dims out
    5)Brightens in, brightens out
    6)remains brighter the entire time
    7)Dims in, Brightens out
    8)Brightens in, no change out
    9)Dims in, no change out
    10)no change in, dims out


    Im leanin towards #7, dims as the rod is thrust into the solenoid, and brightens as it is removed. since the iron rod is a conductor, it would draw some of the mag force away from the solenoid (and therefore the battery) thus making it dimmer... and then when it is removed, the bulb would brighten back to its original state....

    is this reasoning correct? any help?
  2. jcsd
  3. Oct 24, 2004 #2
    solved. nevermind
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