Pure water does not conduct electricity very well. However, when
certain substances are dissolved in water, the solution does
conduct electricity. You can make a simple device that shows how
well a solution conducts electricity. This device uses a
flashlight bulb to indicate how well the solution conducts
electricity. The better the solution conducts electricity, the
brighter the bulb will glow. To construct the conductivity
tester you will need: - ● a 12-volt AC adapter - This converts
the 110-volt electricity from a wall socket to safer 12-volts.
It must be 12 volts AC, not DC, because DC will not work for
this. You may have a suitable adapter around the house from an
old device you're no longer using, or you may get one from an
electronics store (e.g. Radio Shack, catalog number 273-1631). -
● an audio cable with a 1/4-inch or 1/8-inch monaural plug on
one end - The plug will become the probe for testing
conductivity. You may have an unused cable around the house.
What is on the other end does not matter b