Science Buddies: "Ask an Expert"

I am conducting the electrolyte challenge experiment and am quickly growing frustrated!

I have set the experiment up according to the directions and I have also set it up according to the directions posted on the forums here and neither way is yielding any results. I have insulated copper wire that has the insulation removed. I am wrapping the wire tot he battery because I could not find the battery clip. I have the experiment set up both ways and every time I get .01 on the multimeter. I am using a fluke meter that is rather old but still seems to be functioning. I can move it to volts and it is measuring the 9 volts from the battery.

What could I be doing wrong that I am not getting any different results submerging my sensor in the various liquids? I am using OJ, Gatorade and Coconut Water... all of which should have enough electrolytes to get a reading.

I have a feeling that it is in my set up but I can't figure out anything that is different that could be causing the readings to all be .01 or 0. Could I be incorrectly using the multimeter or could it not be working correctly?

Thank you for any help you can offer!

emsstacey - The fact that you are reading the 9 volts from the battery when the Fluke meter is set to DC voltage suggests that the electrolyte is conducting and you are properly putting the meter, battery and electrolyte in a series connection and that the polarity is correct. I think you may have an improper range set on the meter. You should be set to DC milliamps, probably starting in a lower range like 0-100 mA, then increasing or decreasing as your experiment requires. Make sure your probes are connected properly to the meter for DC current. As a quick check, I just took about 1/4 cup of tap water, added about a pinch of salt (barely enough to taste a faint saltiness) put it into a circuit with a 9 volt battery and it immediately read about 25 mA. I'm sure something like Gatorade is as conductive than the mixture I made. Hope this helps.

Rick Marz

Hope you've been able to move forward with your project, but in case you're still having trouble we also have a guide to multimeters here:

https://www.sciencebuddies.org/science- ... eter.shtml

And I'm including a link to the description of your project for everyone's reference:

https://www.sciencebuddies.org/science- ... p053.shtml

Amanda

Thanks! I was finally able to get some readings that are consistent with my hypothesis. They do not seem to be in the same units but at least I'm showing something!

I put the red lead in the amps setting (in the mA setting... I was getting nothing) and then turned the dial to mA and pushed the range button until it showed 30 instead of 300. I was able to get 0.0 for distilled water, 0.06 for coconut water, 0.03 for Gatorade and a few other liquids. These results were repeatable for a total of 3 times, so I am fairly certain they were accurate and the changes were due to the varying electrolyte concentrations.

Thank you for your help!