.. 2.14

Resistance of water, using AC
=============================

**Objective**

Measure the resistance of ionic solutions, using both DC and AC
voltages. We have used normal tap water. Try measuring the resistance
using a multimeter first.\begin_inset Separator latexpar\end_inset

.. image:: schematics/res-water.svg
	   :width: 300px
.. image:: pics/water-conduct.png
	   :width: 300px

**Procedure**

-  R1 should be comparable to R, start with 10k.
-  Enable A1 and A2
-  Calculate the resistance as explained in section
   `2.4↑ <#sec:Measure-resistance-by-comparison>`__

**Discussion**

Observed values are shown in the table. The DC and AC resistances seems
to be very different. With DC, the resistance of the liquid changes with
time, due to electrolysis and bubble formation. The resistance does not
depend much on the distance between the electrodes, the area of the
electrode is having some effect. The resistance depends on the ion
concentration and presence of impurities in the water used.

Try changing the distance between electrodes. Try adding some common
salt and repeat the measurements. Why is the behavior different for AC
and DC ? What are the charge carriers responsible for the flow of
electricity through solutions ? Is there any chemical reaction taking
place ?
