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Homework Help: PLS HELP electric motor project

  1. Apr 22, 2005 #1
    hey there if any one can help i'd be very grateful.
    i have a science project :cry: and i have to construct a working electric motor. i have to make it spin as fast as possible so i did some research and found out about something called a split ring commutator. i still dont understand what it looks like and where it is positioned in the armature. Also what are the brushes and their role??? :confused: any help or tips u can give will be helpful.
    thank you to anyone who helps :smile:
  2. jcsd
  3. Apr 22, 2005 #2


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    Incidentally I did the exam same project in grade 12 and I still remember enough of how it works. I'll start with the whole reason why the motor works. You have two permanent magnets spaced apart with opposite polarizations (north or south) and a set of electromagnets rotating between them. The point is to make the electromagnets rotate continuously. It's rather simple in principle to do this: when the electromagnets are rotating towards the permanent magnets, they must have an attractive force (so opposite polarizations), and when they have passed them, they must have an opposing force (same polarizations).

    To do this, you have to be able to adjust the flow of the current. That's what the split ring commutator does. It's basically a circle with the surface covered in a conductive material (I found that aluminum foil worked well). However, the conducting material is not of one piece but of two pieces each wrapped halfway around the ring. The brushes are two wires (essentially) that are set-up to bridge contact between the conducting material and the electromagnets. What should happens is as the motor rotates, each brush for each electromagnet switches between the two conducting materials on the ring, thereby changind the direction of current, thereby changing the polarizations of the electromagnet.

    If you don't like my explanationg (it's a little wordy) try this one from wikipedia http://en.wikipedia.org/wiki/Commutator_(electric) .

    and just a curiosity question, is the teacher who assigned this project names Mr Mildon?
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