1/2 cup Deionized (or Distilled) Water (Regular tap water can be used, but the resistance of the dough will be lower.)
Circuit
battery pack
batteries
10mm or 5mm LEDS
Instructions
Conductive Dough
Mix water, 1 cup of flour, salt, cream of tartar, vegetable oil, and food coloring in a medium sized pot.
Cook over medium heat and stir continuously.
The mixture will begin to boil and start to get chunky.
Keep stirring the mixture until it forms a ball in the center of the pot.
Once a ball forms, place the ball on a lightly floured surface. WARNING: The ball will be very hot. We suggest flattening it out and letting it cool for a couple minutes before handling.
Slowly knead the remaining flour into the ball until you’ve reached a desired consistency.
Store in an airtight container or plastic bag. While in the bag, water from the dough will create condensation. This is normal. Just knead the dough after removing it from the bag, and it will be as good as new. If stored properly, the dough should keep for several weeks.
Insulated Dough
Mix solid ingredients and oil in a pot or large bowl, setting aside ½ cup flour to be used later.
Mix with this mixture a small amount of deionized water (about 1 Tbsp.) and stir.
Repeat this step until a majority water is absorbed by the mixture.
Once your mixture is at this consistency, knead the mixture into one “lump”.
Knead more water into the dough until it has a sticky, dough-like texture.
Now, knead in flour to the dough, until a desired texture is reached.
Store in an airtight container or plastic bag. While in the bag, water from the dough will create condensation. This is normal. Just knead the dough after removing it from the bag, and it will be as good as new. If stored properly, the dough should keep for several weeks.
Circuit
Start by taking two pieces of conductive dough
Place a wire from the battery pack into each one making sure the two pieces of dough do not touch
Close the circuit by placing a wire from an LED into each piece of dough. If the LED doesn’t light up, flip it around.
Close the circuit, now push the pieces of dough together, you have created a short circuit. To fix it, place a piece of insulating dough between the pieces of conductive dough. The light shines again.
Science Behind It
The lemon juice is able to carry the electric current from the battery to the LED. The reason why the lemon juice works as a conductor is because the acid in the lemon juice reacts with one wire to create an electrochemical reaction which generates a small potential difference which exchanges electrons to reach a lower energy state; this creates the electric current to power things.
Tips
For older members you can have them make their own dough, but for younger members we suggest the project leader makes it before the meeting. After showing the members how to do a basic circuit let them experiment on their own. Also for older members you can have them experiment with the dough to make it fully electric and not have them use the batteries. For this you would need to substitute all the water for lemon juice and use more salt.