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Ohms Experiment Help!

  1. Jan 28, 2007 #1
    Alright, I'm a student and doing a science fair experiment for a little extra credit. Here's the link to where I found it online. http://www.sciencebuddies.org/mentoring/project_ideas/Elec_p019.shtml?from=Home

    I don't get it, at all. I just tried it and every time I measured it the Ohms, DC, and AC were all the same. I don't know what to do, I got about a week left to do this, and I'm completely lost. Anyone else have an idea? This just doesn't make sense to me...:frown:
  2. jcsd
  3. Jan 28, 2007 #2
    What specifically don't you understand? I'll try to make it clear to you.
    Last edited: Jan 28, 2007
  4. Jan 28, 2007 #3
    Alright, well, here's what I did...

    I took a 6v battery, took a wire with alligator clips at both ends and hooked it on the battery and the ohmeter. Then, I took another wire, hooked an alligator clip on it, and connected it to the empty spring on the battery. Then I would complete the circuit with other wires. However, whenever I did this, even with completely different gauges and length, all the results were the same, and I thought they should be different.

    Any ideas?
  5. Jan 28, 2007 #4
    Don't measuring how many volts are in the entire circuit. What you should be noticing is the change in how many amps go through the different gauges of wire. I am assuming you have a volt meter. First check the resistance in different gauges of wire using your volt meter, or go to this site which can tell you the ohms in a wire per 1000ft. The amount of current you will get will depend on the voltage of the battery and the resistance in the wire. An equation that will be very useful for this experiment is
    Example- Say you use your 6 volt battery with a wire that has 2ohms of resistance. Then you would say the current is 3 amps because, (using algebra) 6 volts/2ohms=3amps.

    To sum it all up, what this project looks like its looking for is the resistance in different gauges of wire.

    Hope this helps
  6. Jan 28, 2007 #5
    Alright, I think I'm going to change my project from comparing resistance to comparing volts, or amps. Because like I said, every time I would hook up the wires, the ohms would be the same.

    So thanks!
  7. Jan 28, 2007 #6
    Why are you using an ohmeter with a power source (battery)? This is not the way the ohmeter is meant to be used. I'm not sure you understand what you are supposed to be doing. And I don't think that you will have any better luck measuring volts or amps because resistance is simply a ratio of volts/amps. Can you draw a circuit for us?
  8. Jan 28, 2007 #7
    Measure the resistance in the wires themselves not the battery.
  9. Jan 28, 2007 #8
    Hover, he is not going to get a usable reading measuring the resistance of various gauges of wire with an ohmeter. It is unlikely he has access to a meter that is able to measure that accurately at very low ohm readings.
  10. Jan 28, 2007 #9
    Wow. I just read the link he provided in the first post. They are instructing him to wire the ohmeter in series with the circuit. There is nothing else in the circuit. Just wire, alligator leads and the ohmeter. Who could expect results that make any sense with that?
  11. Jan 28, 2007 #10


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    Wow is right.
    That's horrible.
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