# Conductivity, altered by a magnetic field?

Dingle

## Main Question or Discussion Point

Conductivity, altered by a magnetic field???

Hi

Im a highschool student studying physics.

I conducted an experiment that measured the conductivity of KCl electrolytic solution vs. a change in concentration.

Anyway, i had a magnetic stirrer stirring the solution in a beaker when the conductivity probe from a EDT Series 3 RE387Tx Conductivity meter was inserted to take a reading.

Now the question is,
Does the magnetic field created by the magnetic stirrer also affect the Current flowing between the conductivity meters electrodes and therefore the CONDUCTIVITY!?
(plz say no ! )

PS: The conductity meter puts a small amount of AC through the solution.

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Integral
Staff Emeritus
Gold Member
My bet would be yes. Sorry! :)

The rotating magnet also creates a AC field, it is not clear how the conductivity meter would separate contributions due to the field it generates vs that created by the rotating magnet.

I am currently working on a process which uses conductivity to control the concentration of a chemical (TMAH), we have found that when our heaters are on we have a higher conductivity reading. So you are not alone in being messed up by outside effects on conductivity.

Chi Meson
Homework Helper
Since the magnetic stirrer is rotating, it would create an ac potential in the solution, but I would think that the frequency of rotation of the stirrer would have to be synchronized with the conductivity tester in order to produce a steady reading.

Am I wrong here?

IF you could, see if changing the speed of rotation changes the reading. My inclination (without knowing specifics) is that the stirrer would not contribute much significant current unless you are operating with very precise equipment

Integral
Staff Emeritus
Gold Member
Actually an expesive, precise, conductivity meter may do exactly what you are wanting. That is does noise rejection, however this is a high school lab, I would bet that they have pretty basic equipment.

A good check, would be to check the conductivity of some DI water, on and off the stirer, compare conductivities.

Remember in any High school/college physics lab a well thought out explanination of errors should be worth more then an error free experiment.