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Homework Help: Help me Modify 11th grade Electromagnet project

  1. Nov 21, 2009 #1
    1. The problem statement, all variables and given/known data
    I'm in 11th grade and I'm in an honors physics class. Everyone has to do a science fair project and the teacher said that mine is too easy. Mine is which of the following factors affects the strength of an electromagnet the most: # of coils, thickness of the wire, the voltage of the power source, and the diameter of the core. I've already done a proposal of this that is 8 pages, and it is too late to change to an entirely different topic. Can you guys give me suggestions as to how to turn this into an 11th grade level project? Use my problem about factors that affect strength of an electromagnet the most if you can, but modify it so that it doesn't seem like an elementary project. With your suggestions, please give me tips on how to do them.

    What grade level do you think my project is? Be honest.

    2. Relevant equations It doesn't have any.

    3. The attempt at a solution I just don't know what to do. Please help.
  2. jcsd
  3. Nov 21, 2009 #2


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    "Affects the strength the most" is too simple for grade 11. Why not find the quantitative effect of each? That is, if you double the number of turns, by what factor does the strength increase?

    If you do any research at all, you will find that voltage and wire diameter do not directly affect the strength of the magnetic field produced. There is a better measurable quantity to use, though it might be interesting to do the wire diameter with a constant voltage, too.

    How will you measure the "strength"? If you have a very sensitive current meter (galvanometer or microammeter) you may be able to make a magnetic field strength meter. Otherwise you will have to see how many paperclips you can lift like they do in junior high. It has merit but you won't be sure just what you are measuring.

    Note well: connecting a galvanometer or microammeter to a power supply or battery will instantly destroy it. If you wish to borrow one, you will have to be pretty convincing that you will not do that!
  4. Nov 24, 2009 #3
    Does anyone else have any other good tips? I need all the help I can get. My teacher

    expects a lot from these projects and I don't want to embarass myself.
  5. Nov 24, 2009 #4
    Yup, you could perhaps try to model an empirical relation linking magnetic field strength of the electromagnet to the various variables that you considered. As Delphi mentioned, "voltage and wire diameter do not directly affect the strength of the magnetic field produced". The better measure to use would be current flowing in the wire, which depends on the voltage across and resistance of the wire, especially since it is the current that is responsible for the magnetic field.
    As for measuring the magnetic field strength, I'll say go for the easy way out, using a Hall probe lol.
    In all though, your 'electromagnet' is not much more than a solenoid, and I'm afraid that the magnetic field strength of it has been rather well studied (and within high school syllabus if I'm not mistaken)
  6. Nov 24, 2009 #5


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    You might find it interesting to measure the Earth's magnetic field at your location. The easiest and most flamboyant method is to make a skipping rope out of wire. If two people swing the wire really fast (too fast for skipping), a voltage will appear across the ends that you can measure with a very sensitive volt meter (microvolts). Adjust the direction of the swinging to get the best voltage and you can use your generator formula to deduce the strength of the magnetic field from the measured voltage.
  7. Nov 25, 2009 #6
    These are all good tips, and I'm considering some of them. Does anyone else have any last tips or thoughts on my project? I need to explore all possible options because this is a big part of my grade.
  8. Nov 30, 2009 #7
    Sorry if I am disturbing you guys, but do you have other suggestions? I like Delphi51's idea of finding the quantitative effect of each and FightFish's idea of the empircal relation, but can you guys explain these ideas more clearly because I am not that smart? I would greatly appreciate it. Also, can you guys tell me how long your ideas will approximately take if I decide to do them and all the materials that I should use?
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