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.
Step 2
Put the blocs together as shown and plug in the Jack Plug
into the IN block.
Step 3
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. The sound level of the BLEEP will
change depending on how hard you press or how much your
hands are sweating (because of telling lies!).
You can also do this with two people. 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 will find that
the Logiblocs can be triggered through you
both! This is because your bodies also can
conduct electricity.
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