Make Your Own Parts

Project Number: 33

Description: Build the circuit, set the meter (M6) to the 0.5mA setting, and set the slide switch (S5) to position B. Make your parts using either the water puddles method (A), the drawn parts method (B), or the pencil parts method (C). Touch the metal in the jumper wires to your parts and read the current.

Methods: Method A (easy): Spread some water on the table into puddles of different shapes, perhaps like the ones shown here. Touch the jumper wires to the points at the ends of the puddles. Method B: (challenging): Use a SHARP pencil (No. 2 lead is the best) and draw shapes, such as the ones shown here. Draw them on a hard, flat surface. Press hard and fill it in several times until you have a thick, even layer of pencil lead. Touch the jumper wires to the 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. Method C (adult supervision and permission required): Change the setting on the meter to the 50mA scale. Use some double-sided pencils if available, or VERY CAREFULLY break a pencil in half. Touch the jumper wires to the black core of the pencil at both ends.

Snappy: Resistance = Voltage / Current, so you can use battery voltage (3.6V) and the current you measure to find the resistance of your puddles and drawings. Long narrow shapes have more resistance than short wide ones. The black core of pencils are graphite, the same material used in the pivot stand.