LIE DETECTOR
We can use the Spy Kit to make a Lie
Detector. This uses the effect that when
people do not tell the truth they usually
sweat which increases the electrical
conductivity of their hands.
Step 1
Make two hand sized aluminium foil pads and
lay them side by side on a table, making sure
that they do not touch. Fix with tape the
metal ends of the Jack Plug wires with
some sticky tape, one to each piece of
foil.
Put the blocs together as shown and plug in
the Jack Plug into the IN block.
Pre-record “Liar!” or “That’s not true!” by touching
the pads together to trigger the blocs with the slider
in the Record position
●
. Push the slider switch
back to Play
➤
.
Now keeping the pads separate place one or two fingers
on one pad. Get someone to ask you some questions about
you or your friends. Each time you give either a true or false answer put one
or two fingers from your other hand onto the second pad. Depending on
how hard you press or if your hands are sweating (because of telling lies!) the
“True” or “False” message will be
played back.
You can do this with two people
using the Lie Detector. Put your
right hand on the right pad while
your friend puts his or her left hand
on the left pad. Ask each other
questions and then join your free
hands together. You should find
that the Logiblocs can be triggered
through you both!
17
