Elenco Snaptricity&reg - Manual (Page 25)

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Educational Corner:
Make Your Own Parts Project #15
Build the circuit shown, set
the meter (M5) to the 1mA
setting.
Assembly
Make your parts using either the water puddles method (A), the
drawn parts method (B), or the pencil parts method (C). Set the
slide switch (S5) to position B to turn on the circuit. Touch the metal
in the jumper wires to your parts and read the current in milliamps.
Operation
1mA
You can use Ohm’s Law to
measure the resistance of your
puddles and drawings. The
voltage is about 4.5V, and use the
current measured on the meter.
Voltage
Current
Resistance =
Snappy says: long narrow
shapes have more
resistance than short wide
ones.
1mA
Method A (easy): Spread some water on the table into
puddles of different shapes, perhaps like the ones shown
below. Touch the jumper wires to points at the ends of
the puddles.
Method C (adult supervision and permission
required): Change the setting on the meter to the 1A
scale. Use some double-sided pencils if available, or
VERY CAREFULLY break some pencils in half. Touch the
jumper wires to the black core of the pencil at both ends.
The black core of pencils is
graphite, the same material used
in resistor components
throughout the electronics
industry.
Method B (challenging): Use a SHARP pencil (No. 2
lead is best) and draw shapes, such as the ones here.
Draw them on a hard, flat surface. Press hard and fill in
several times until you have a thick, even layer of pencil
lead. Touch the jumper wires to points at the ends of the
drawings. You may get better electrical contact if you wet
the metal with a few drops of water. Wash your hands
when finished.