conductors experiment help

[ChrisJ]

I am doing a science fair project on conductors of electricity. My question for the project is "Which materials are the best conductors of electricity?" I did research and found out that metals are good conductors and non metals are usually not good conductors. I am having trouble writing my hypothesis. I think that the metals are going to light a lightbulb in my circuit experiment, and non metals won't. I think metals are going to be the best conductors, but I don't have a good guess about which metal will be the best. My teacher says that my hypothesis has to be more specific, and I can't just say that I think metals will be the best conductors, and some metals will be better than others. Help!! I am worried that I can't do the project because my research already told me that metals are better conductors than non metals. I also have no idea which metal will be better than which. I am worried that I have to change my whole project, and I don't have time to start something completely different.

[adance]

Hi ChrisJ

I think this is a very reasonable project for your grade level.

This is out of my field, so I consulted an expert of my own. It seems like predicting conductivity is a tricky question.

One thing you might try is to look up the thermal conductivity of the metal--how quickly it transfers heat. Try here, http://hyperphysics.phy-astr.gsu.edu/hb ... thrcn.html

Another thing to consider is the metal's density, maybe conductivity might have something to do with how closely the atoms are packed? See http://www.rpi.edu/dept/cie/mncr/ebeams ... ode28.html

But as you may have guessed, the best way to find the answer will be to do your experiment! Remember your hypothesis is an educated guess, it's OK if it turns out to be incorrect.

Good luck.

[MelissaB]

Hi,

I have moved this topic into the physical sciences portion of the board because that's where our electricity experts reside! Good luck.

[ChrisJ]

Thanks for helping. Sorry I wrote in the wrong place.

[MelissaB]

No problem, lots of people do .

[fmcwilliams]

Hi ChrisJ,

I also think that this project is a very good choice, and since you have already put a lot of time and thought into it you will do fine. To help you with your hypothesis, here is a link to a page “All About Circuits; Conductors, insulators, and electron flow” that discusses the information that you are looking for. http://www.allaboutcircuits.com/vol_1/chpt_1/2.html

Also, remember what Amber said about your hypothesis. It does not have to be correct, Its a guess based on your research, which you will test with your experiments.

[ChrisJ]

I did my experiment with the light bulb, but all the metals lit up the bulb brightly. Only graphite lit it dimly. I wasn't able to tell from this test which material was the best conductor. I also tried testing the resistance of each material with a multi meter, but I got the same reading for many of the materials. Also, where I put the test tips of the meter on the material changed the readings. The readings also changed if I moved. Is it ok to say that I was able to tell that metals were the best conductors, but that I couldn't tell from my tests which one was the best? I can't think of another way to test the materials to see which one is the best conductor.

[ChrisG]

Hi Chris

Is it ok to say that I was able to tell that metals were the best conductors, but that I couldn't tell from my tests which one was the best? I can't think of another way to test the materials to see which one is the best conductor.

Yes, that sounds like an accurate statement.
I also can't think of another cheap & easy way to quantify the resistivity of metals. One alternative would be to focus on the electrical conductivity of other, less conductive materials (in addition to graphite).

[Craig_Bridge]

Measuring the resistance of good conductors is a challenge for experienced engineers and it takes some rather sophisticated instrumentation methods. Only when you have hundreds or thousands of feet of a small diameter wire will you be able to easily measure it. Metal oxides make relatively poor conductors so I expect part of your experience with the choice of where contact was made changing your results was caused by contact resistance of metal oxides.