Instructions

Game and Knowledge in Electronics-Lab
8
You probably already know that
all metals conduct electricity while
glass, plastic and many other
materials don’t. Build your own tester
using two test cables. When you
touch a conducting object with them,
the LED will switch on. You could
also test a pencil lead, pure water
and lemon juice. You will probably
also find materials that are weak
conductors.
And even your fingers can conduct
some electricity, especially when you
have moistened them with water.
You might have to switch the room
light off in order to see the weak LED
light. Electricity as such is invisible
but you can see its effect, the lit LED
in this case.
What is a conductor and what isn
,
t?
3
Caution
You can only touch the cables
because the battery voltage is
very low with 4.5 V. That means
that the current is very weak.
For larger voltages from a mains
socket (230 V), touching the
cables would be fatal! Never
insert the wires into the mains
plug!