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Securing the
room door
YOU WILL NEED
+ your alarm system
from Experiment 5
+ 1 long wire connector
+ and additional house-
hold items: 9-volt square
battery, aluminum foil (2 x
5 cm), cardboard (2 x 7 cm),
tape, glue, scissors
HERE'S HOW
1. To use your alarm system properly,
you will need a door contact. To
make one, pull the long wire out of
terminal A or B and insert another
long wire into the now-open
terminal. Now lead the two long
wires to the doorframe and secure
them there with tape.
2. Cut a piece of aluminum foil
(around 2 x 5 cm, say) and a slightly
longer strip of cardboard (2 x 7 cm).
Glue the foil to the cardboard strip.
3. Attach the cardboard with the foil
to the door at the same height as
the two wire ends that you already
attached to the doorframe. Be sure
that when the door closes, the two
wires from terminals A and B touch
the aluminum foil.
4. Open the door and see what
happens.
Alarm Systems
EXPERIMENT 7
1
3
25
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