Science Buddies: "Ask an Expert"

I'm unsure whether this is an issue with the multimeter or the water itself, but the reading for the tap water is always around 3.4 or something above 3. Compare this to my reading for the distilled water, which is usually around 2.3. I've scoured websites and the official Youtube video, but I can't figure out why this is occurring. Even when I pour in the tap water, the voltage for the distilled water goes down a little, then right back up and even higher. Any idea on how to fix this or someone who had this problem? The green water is the tap water.


[Administrator note: Project URL: https://www.sciencebuddies.org/science- ... l-pancreas ]

Hi - I'm looking at the picture of your setup, and I don't think you have your conductivity sensor and multimeter connected correctly. Look carefully at FIgure 6 in the procedure here: https://www.sciencebuddies.org/science- ... l-pancreas

and note the connections:

- Conductivity sensor:
- one end to the same row in the breadboard as the lower end of the resistor (it looks like you have this correct
- other end to a jumper wire that connects to the ground bus in the breadboard (it looks like you do NOT have this correct, you have the other end of your conductivity sensor connected to the positive (red) probe of your multimeter with a black alligator clip)

To measure the voltage with a multimeter, see procedure step 5a. You would connect the black probe to the ground bus (you have that correct) and the red probe to the same breadboard row that has the orange jumper wires (you do not have that correct).

Let us know if that makes sense. I would start by removing the multimeter entirely, make sure the conductivity sensor is connected as shown in Figure 6, and then connect the multimeter.