Science Buddies: "Ask an Expert"

I am doing the "electrolyte challenge orange juice vs sports drink" i am getting no readings on my muktimeter when i set it to 200milliamos or 200 microamps( the side with A with a dashed line) i am very confused. I recheked all the connections and i dont think i am doing anything wrong...once i got a reading but i got it on the side with V and a dashed line not amperes side. my readings are coming in negative. I also want to know thag what should be the range for accurate readings..should it be small numbers or big numbers and also if there is any other way to do this project!
I really need help.. My science fair is in 2 days plz help me asap plz

Hello monadas,

From the description in your post it appears that you have the correct multimeter settings (either 200 milliamps or 200 microamps). Since you've re-checked all of your connections you've eliminated a loose connection as a potential problem. My suggestion is to re-check the following items.

Is the positive (+) battery terminal connected to the positive jack on the multimeter, and is the negative battery terminal connected to the ground or negative jack on the multimeter?

Is the conductance sensor that you made submerged in one of your sports drinks or juices (if not you'll have an open circuit)?

Are you using a good, fresh 9V battery?

I don't know the range of amperage readings you might expect to get. A quick search of this forum revealed quite a few posts about the “Electrolyte Challenge” project. Some of these quote readings around 20 to 40 milliamps.

I hope this helps and good luck with your project. Please post again if you have more questions.

A. Norman

Does the battery have to be fresh? i have used the battery a few before should i change it?
and can i use the conductance sensor to do this project? but i think it would be too easy!! help me

Hi monadas,

You might want to try a new battery because you've had some problems getting your circuit to work properly.

The conductance sensor is the drinking straw with wires coiled around it as described in the beginning of the project procedure.
https://www.sciencebuddies.org/science- ... #procedure


I hope this helps. Please post again if you have more questions.

A. Norman

okay i will try buying a battery....but i have another question about the project named " Sliding light: how to make a dimmer switch" i am doing it wihtout the lux meter.. the link is here: https://prezi.com/nb3-mntmhf0e/dimmer-switch/
i am in grade 9. plz tell me if this project if okay for my grade...plz plz

Hi monadas,

The “Sliding Light” project strikes me as a very clever way of showing how a variable resistor works in an electrical circuit. It should be an interesting and informative science project. In my opinion the complexity of this project is similar to that of the “Electrolyte Challenge” project. Because I am not a teacher, I'm not in a position to comment on whether this project is OK for grade 9 students.

I hope this helps. Please post again if you have more questions.

A. Norman

Okay thanks! Do i have to use the engineering process for "sliding light" project or i can use scientific method ( i prefer the scientific method)?

Hi monadas,

Whether you use the engineering process or scientific method will depend on how you approach the project. If your primary purpose is to test a hypothesis about the relationship between two variables in the project, then the scientific method would be more appropriate. If, however, you are trying to revise and improve your design until you reach a specific design goal(s), then the engineering design process will be more appropriate for your project.