United ScientificCNDT01, Electric Conductivity Tester

Love this device for testing solution conductivity in Chemistry High School classroom. Indestructible, easy to clean and easy for students to use and determine results - push button to see lights. Shows results from 1-10 - if no conductivity (reading of 1) to strong conductivity (reading of 10). Allows students to compare ionic compounds (7-10), polar covalent (3-5) and non-polar (1-2) - assuming no contamination. Better and cheaper than the 9-volt testers.

For some reason the designers show that no current is a value of "1". If they would have still had an LED lit but put it as a "0" for no current this would be an excellent device. However, with that flaw you have to spend time explaining to the user (if it is not you), what that flaw is and why it matters. However, at that price and the ease of use, it is still a decent device.

I have purchased these conductivity testers for my classroom in the past. The older models correctly displayed no green lights ("not conductive") when just turned on, or at least in distilled water. The conductivity testers I just purchased showed one green light ("conductive") as soon as I installed the battery. Although the tester would display more green lights if something was really conductive, I want my students to understand that something (like distilled water, a solid salt) is not conductive. I returned these conductivity testers.

Perfect for a science lab if you don’t feel like fiddling with batteries and wire and whatever else to build your own. Does solids and solutions.

Works great in my classroom! Much better than the stuff I've bought from other retailers. Would highly recommend

when on this meter registers at a 1, the same meters we have purchased for lab use in the past measure non conductive substances by not lighting up at all (assume 0). This one lights up to 1 for all substances conductive or not, then increases to 10 from there.