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Science fair followup!

Discussion in 'Electrical Engineering' started by eye guy, Jan 20, 2004.

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  1. eye guy

    eye guy Guest

    First off, A great thanks to all! It's a pleasure (usually the case) to
    find helpful and intelligent people in newsgroups. I hoped for a
    response or two, but instead found a wealth of ideas and suggestions,
    thanks again. Unfortunately, alot of your suggestions were outside our
    budget and/or time we had for this test. Now on with the experiment!

    Indeed the first major foulup with our design was the christmas light.
    It did indeed provide inaccurate resistance, something that our local
    Radio Shack dealer remedied with 10 Ohm and 100 Ohm resistors. We now
    made the resistance a constant in the formula. For a multimeter I
    borrowed a digital one from a friend which measured down to the
    milliampere. We used purchased wires with alligator clamps on the ends
    to ensure as good as possible connections to the coins. In the end, no
    matter whether we used AAA carbon-zinc, AA Alkaline, D Alkaline, 10 Ohms,
    100 Ohms, or 300 Ohms, all the coins gave exactly the same reading.
    Within the time / budget of a 4th grade science fair the results were
    that all the coins conducted the same.

    A trip to the US mint website found that the coins of modern day are all
    made of the same metals, just in different ratios. Based upon this
    information, it's no real surpise that the numbers in this simple
    experiment are all equal.

    A father's curiosity is still researching the wheatstone bridge method
    for personal knowledge. Based upon my son's interest in electricity,
    I'll need it next year!

    Thanks again and GO Panthers!

    Ken in North Carolina
     
  2. ZForce

    ZForce Guest

    If you still have time, try something like making a battery out of lemons,
    or oranges.

    try this link for a how-to

    http://familyfun.go.com/raisingkids/learn/activities/feature/famf119weirdsci/famf119weirdsci6.html


    Have fun.
     
  3. dated Tue, 20 Jan 2004 03:47:31 GMT,
    This is bullshit and you do NOT understand what you are doing.
    Different ratios of metals give different resistances.

    The resistance of a typical coin is far less than a milliohm.
    The accuracy of your testing device is one ohm at best.
     
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