Thames & Kosmos Electronics - Conductivity tester

Conductance
EXPERIMENT 

Conductivity
tester
YOU WILL NEED
 your humidity detector
+ and additional household
items such as a key, eraser,
coin, pencil, toys
HERE’S HOW
1. Get the items ready that you will
want to test.
2. Hold the two bare ends of the long
wires of your humidity detector up
to the key, eraser, coin, etc.
If the materials are conductive, the
green LED will light up; if they do
not conduct electricity, the red LED
lights up.
So not only can your circuit signal
the conductivity of water, it can
also show what other objects are
capable of conducting current.
 WHAT’S HAPPENING?
Note!
Of course, during all your
experiments you have to
be sure that the bare wire
ends do not touch each
other — otherwise your
sensor will not work.
LED1
LED2
T1
+
–
T2
A A C
C
R1
 kΩ
R2
 kΩ
R3
 Ω
R4
 kΩ
R5
. kΩ
R
 Ω