How to Make a Photon Flower That Lights Up When You Water It with Lemon Juice
Have you ever made a battery out of a lemon? If you poke a copper wire into a lemon and poke a zinc-coated nail in next to it, you can measure with a voltmeter that the lemon produces between 0.5 and 1 volt. The copper is the "cathode", or positive end of the battery, the zinc is the "anode", or negative end, and the lemon juice is the "electrolyte". This instructable shows you how to make an artificial flower in which each petal of the flower is like a lemon battery cell. When the petals are connected in series and moistened with lemon juice, an LED at the center of the flower lights up. This instructable builds on the ideas of Madaeon but uses a design that doesn't require soldering.
You will need:
- Eight zinc-coated nails.
- A paper towel cut into eight 1.5" x 1.5" patches.
- Uncoated copper wire.
- A cork.
- Lemon juice.
- An LED. This project works best with an LED that has a low forward voltage and low forward current. I used a 1.6v 1mA LED. Other LEDs may work but may require more cells to light up brightly.
1. Roll a patch of paper towel around a zinc nail and wind a 12" copper wire on top of that. Leave a 4" tail of wire. Make eight of these.
2. Push the nails into the cork radially. (If you have trouble, you can drill small holes in the cork first.) Next connect the petal battery cells in series by connecting the positive (copper) end of one cell to the negative (zinc) end of the next cell. To do this, connect a copper wire tail to its neighboring nail's head. Be sure to make a good connection: wrap the wire tightly at least four times around the nail. Continue connecting tails to heads. However, don't connect the last tail! Doing so would cause a "short circuit" that could damage your battery. The last tail and nail head will be connected to the LED in the next step.
3. LEDs need to be connected with the correct polarity; that is, connected in a circuit with positive-to-positive and negative-to-negative wiring. Look carefully at your LED and you will see that one lead is longer than the other. This is the positive lead. Connect it to the positive lead of your battery, which is the last (unconnected) copper tail. Twist the positive lead of the LED onto the last tail of your battery. Be sure to intertwine the leads so that they have a good connection.
Twist a 2" length of copper wire around the LED's negative lead, and wrap the other end around the remaining unconnected nail head (which is your battery's negative connection).
4. The moment of truth! Place a drop of lemon juice on each petal's paper towel. When all of the petals are moistened, the LED should light. Yay!
If the LED doesn't light, check that all of the connections are good. Make sure that on each petal, the copper wrapped around the paper towel is not touching the copper wrapped around the nail head.
The LED should stay lit for half an hour or so until the paper towels dry out. You can light it up again simply by adding more lemon juice.
