Conductive Play Dough Circuits

Safety Notes

• Only use low-voltage batteries (9V or less)
• Never connect to wall outlets or high-voltage sources
• Adult supervision required for cooking the dough
• Store playdough in a sealed container to prevent drying

Instructions

Part 1: Make the Conductive Playdough

1. In a saucepan, combine:
2. 1 cup flour
3. 1/4 cup salt

4. 3 tablespoons cream of tartar (or 9 tablespoons lemon juice)

5. Add the liquids:

6. 1 cup water
7. 1 tablespoon vegetable oil

8. Food coloring if desired

9. Cook over medium heat, stirring constantly until the mixture thickens and forms a dough consistency (about 3-5 minutes).

10. Remove from heat and let cool until safe to touch.

11. Knead the dough until smooth and pliable.

12. Store in a sealed plastic bag when not in use to prevent drying.

Part 2: Build Your First Circuit

1. Shape the dough:
2. Roll two separate balls or snakes of playdough

3. Keep them at least 1 inch apart - they must NOT touch or the circuit will short!

4. Insert the LED:

5. Look at your LED - it has two legs (one long, one short)
6. Insert the long leg (positive/anode) into one ball of dough

7. Insert the short leg (negative/cathode) into the other ball of dough

8. Connect the battery:

9. Clip one alligator wire from the battery's positive (+) terminal to the dough ball with the LED's long leg

10. Clip the other wire from the battery's negative (-) terminal to the dough ball with the LED's short leg

11. Watch it light up!

12. If the LED doesn't light, try switching which wire goes to which dough ball
13. Make sure the dough balls are NOT touching each other

Part 3: Experiment Further

Try these experiments to learn more about circuits:

1. Resistance test:
2. Make the playdough "wires" longer or thinner - does the LED get dimmer?

3. This shows how resistance affects current flow

4. Multiple LEDs:

5. Add more LEDs in series (one after another through the dough)

6. Try parallel circuits (each LED in its own dough path)

7. Different components:

8. Replace the LED with a buzzer or small motor

9. What happens?

10. Shape sculptures:

11. Create playdough creatures with glowing LED eyes
12. Build a lighthouse with a blinking light

What's Happening?

Conductivity through Ions:
The salt (sodium chloride) in the dough dissolves in the water to create ions - charged particles (Na+ and Cl-). These ions are free to move through the wet dough, carrying electrical current from one terminal of the battery to the other.

The path is: Battery (+) → Alligator clip → Dough 1 (ions carry current) → LED → Dough 2 (ions carry current) → Alligator clip → Battery (-)

Why Salt Matters:
Pure flour and water don't conduct electricity well. The salt is essential because:
- It breaks apart into positive (Na+) and negative (Cl-) ions in water
- These mobile ions act like tiny electrical carriers
- More salt = more ions = better conductivity

Circuit Basics:
- The LED only lights when there's a complete circuit (loop) for electricity to flow through
- If the two dough balls touch, electricity takes the easy path directly through the dough (short circuit) and bypasses the LED
- The LED requires a certain direction of current flow (that's why one leg is longer)

Resistance:
When you make the dough path longer or thinner:
- Electricity has to travel through more dough
- More collisions occur between ions
- This creates resistance, reducing current
- Less current = dimmer LED

This is how real electrical wires work - longer, thinner wires have more resistance!