Testing the conductivity of solutions can give important insights into the nature of, and the particles in, a solution. This conductivity meter uses a green and a red light emitting diode (LED) to quantitatively measure the conductivity of a solution. The green LED requires more voltage than the red LED. Immersing the electrodes into a weakly electrolytic solution results in a dim glowing of the red LED while the green LED remains off. A strong electrolyte solution will cause both the red and green LEDs to glow. The scale below, which is also affixed to the meter, can be used to measure and compare the conductivity of various solutions. The meter is sufficiently sensitive that it will display low conductivity for 70% alcohol solutions and medium conductivity for tap water.
This conductivity meter is safe—no electric shock is possible because only a 9-volt battery is used. And, because it is battery operated, the device is entirely portable. The meter cannot easily be shorted out, particularly since an ON/OFF switch is provided to disconnect the circuit even during storage. The electrodes are easily interchanged or replaced.
|Scale||Red LED||Green LED||Conductivity|
|0||Off||Off||Low or None|
|4||Very Bright||Medium||Very High|
Flinn Catalog/Reference Manual Page 204
Flinn Middle School Catalog/Reference Manual Page 181