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Some help with Ohms and resistance?

hey guys, i know there are a lot of you guys out there that deal with electrical dealings and such, and im doing a science project, dealing with electrolysis, so i decided to compare two electrolytes to see which has a lower resistance, and to see which would be more efficient therefore. SO, the only problem is, i have no multimeter, voltmeter, or anything close to it, and i don't know anybody 'round her that does..So im asking you, could you help me with seeing the resistance of-
* water (tap water)
* water with Epsom Salts
 * and water with Baking soda powder (either will work, but i would prefer powder, as baking soda is said to cause chlorine gas, and what not..whichever you have works)

If you could take a picture of yourself using the multimeter, that would be stellar, thats all for now, 
come on guys, i know you know this stuff, and i just cant figure it out, counting on you :)
 

yellow_multimeter1.gif
28 answers
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Jan 5, 2010. 2:35 PMsteveastrouk says:
Got a compass ? 
Jan 5, 2010. 2:49 PMsteveastrouk says:
Make yourself an ammeter.....How ?
Jan 5, 2010. 3:06 PMsteveastrouk says:
What would happen if you put a current carrying wire near it ? 
Jan 5, 2010. 3:17 PMsteveastrouk says:
So. If you have a nice fresh battery, and a certain resistance, and say our compass  deflects 20 degrees.... With another resistance say 1/2 as much, will more or less current flow ? What will be the effect on the meter ?

This method is probably part of how Georg Simon Ohm actually DID his research.
Jan 5, 2010. 11:42 PMlemonie says:
Like I said previously - you want to know your solutions, and arrive at figures in ohms per unit length with respect to concentration. Or be sure to make the concentrations and distance the same at least

L
Jan 7, 2010. 2:48 PMlemonie says:
I've said this at least twice - know your solutions. What concentrations were they at?
De-ionised (very pure) water is in the MOhm range, your results seem to be rather high - how did you do it?
(The acid seems OK)

L
Jan 7, 2010. 4:47 PMlemonie says:
How did you do it, how much of the minerals did you dissolve in how much water?

L
Jan 5, 2010. 1:45 PMlemonie says:
No. You need to show your initiative and find a work-around.
Have you got LEDs and a battery?
Standardise some solutions:
1g/100ml, 10g/100ml, 20g/100ml etc. see what will light things, you can calculate to some extent.
Baking powder does not contain chlorine, "bleaching powder" does though.

L
Jan 5, 2010. 2:51 PMsteveastrouk says:
Salty water does though. Can you crack brine to chlorine ? 
Jan 5, 2010. 3:04 PMlemonie says:
Yes I did that, years ago. Distressed the carpet a bit, smelled-a bit, I think I chlorinated Flora-spread or similar...

L
Jan 5, 2010. 3:08 PMsteveastrouk says:
I read a classic science fiction story, by the late, great Colin Kapp, the Survival Game where the protagonist survives, and survives well using his technical skills - electrolysing water to make bleach as the precursor to something else.
Jan 5, 2010. 11:39 PMlemonie says:
Well you can get to chlorate, then fire & possibly explosives.

L
Jan 5, 2010. 2:12 PMlemonie says:
Make sure you know how your solutions are prepared, keep the electrodes at measured distances.
It's going to be relative to start, but you could get close by visual comparison. E.g. you wire one identical LED through a known resistor, change the distance between electrodes until you match the brightness. Ultimately you have to produce a figure (tied to concentration) which is Ohm per unit length. Or you go cleverer than that by differing concentrations (MS Excel graph) and get Ohms per unit length proportional to molar concentration.
It's more difficult than using a multimeter, but it's a more intensive use of your mind, and ought to score more points.

L
Jan 5, 2010. 2:52 PMsteveastrouk says:
Much more complicated.
Jan 5, 2010. 1:58 PMsteveastrouk says:
What can't you figure out ? Use some ingenuity, and make a meter.
Jan 5, 2010. 2:40 PMorksecurity says:
Borrow multimeter. (Or buy one; you can get simple ones for under $10.) Set to highest resistance range. Stick probes in liquid. Measure results. Note that the results may vary depending on the size and shape of the container and placement of your test leads; if so, you should propose some theories on why that's happening, and if not you should propose some theories on why not.

The reason you do homework is to learn how to do things, not just to get the answer. One of the things you need to learn is how to allow yourself enough time to complete a project.

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