If you’re absolutely lifeless like me, try measuring the resistance of tap water…
Too lazy? Here, let me do it for you:
Note: The meter is reading negative ohms.
And a video too:
Sorry about the background noise. It’s the loud Vibration Reduction feature on my Nikon lens. Absolutely not meant to record videos.
Is it only with my multimeter? Just curious. 
now add one tablespoon of salt at a time, let it dissolve and take measurements, ok? Will the resistance go up or down? why? what are real life applications for your experiment? will a change in temperature affect the results? Class dismissed!
(also consider the surface area of the conducting surfaces)
Are you guys saying that getting negative ohms is common/normal?
I’ve never experienced it without intentionally hooking up a voltage source to the resistance meter.
I would say that you really are not experiencing negative ohms (Or an abundance of connectivity/absence of resistivity) and that the current is flowing from the negative to positive on the meter instead of positive to neg (Backwards connectors) most multimeters express this by making the value a ‘negative’ value even though it is really not ‘negative’. It’s just a symbol to tell you which way the current is reading.
Water itself has no electrical properties (other than an isolator) but the minerals and substances that are easily dissolved and mixed in it gives it it’s conductive properties. Thus why electrical devices are often washed/cleaned with distilled water. You’d be amazed at the cleaning power of these new ‘super-dishwashers’ that are used in manufacturing and medical fields, all without much risk to damage the devices! High frequency cleaning is quite amazing for getting rid of small particulate.
The dust that floats around in the air is conductive (Once it settles) so even this small amount of material can increase the connectivity of materials such as water when it mixes with it. If you don’t believe me grab one of your bright’ish torches and walk around at night, aim it sideways and you’ll see the stuff in the air! It’s one of the reasons you can see beams at all since the light is bouncing off of all the little particles in the air until it hits it’s target and bounces back (So you can see it).
Thank you for your detailed explanation. Water’s conductivity does significantly increase with the addition of solutes (water is the solvent), but it still doesn’t explain why current would be going backwards the test leads.
At first, I suspected EMI from the drain block but I ruled that possibility out after I poured it into a bowl and measured the resistance. Same result:
My cheapo DMM gives pretty random results all over the scale. Goes first up and over the limit, then again down etc…
Same here, mine bounced back and forth the ranges, and surprisingly when I set it to manual ranging, it read different values! (as you can see in the video)
It read negative ohms in the 600M Ohm range, 14K Ohm in the 60K Ohm range, and so on.
It’s crazy!
Ok ... how about ice ?
I find that when i’m dehydrated and have dry hands in work, when i get a shock, it doesn’t hurt as much
Try switching to mV DC and take a reading.
Have you tried the same measurements using dehydrated water?
Dehydrated water? Do you mean distilled?
No, I often buy it when I go hiking, it saves a hell of a lot on weight.
If you really want to measure the resistance of water, you’ll have to use something that isn’t bi-metal like your test leads. You’ve created a battery by submerging your leads in the water like that - which is why you’re getting negative ohms.
Take something that’s stainless steel… PURE stainless steel… Like a good kitchen butter knife or something like that. Put two of them in the water, and then touch your test leads to an exposed area of the knives. This should give you a much more reasonable measurement.
PPtk