As part of a generation of children growing up in an increasingly green and eco-conscious world, things like low-energy light bulbs and hybrid cars are the norm for your child. Making a clock that runs on citrus power is not only a powerful way to reinforce the idea that there are alternative energy sources to be found everywhere, but it's also a great way for her to learn more about electricity and conductive materials. Note that though using alligator clips is ideal for this experiment, you can only use them if the terminals in the battery compartment of the clock are large enough to clip onto. If they are not, you will need to use electrical tape to secure the ends of the wire to the terminals.
Skills Being Practiced
- Scientific method
- Basic understanding of how electricity works
- Exploration of conductive materials
What You Need
- 2 large lemons or other citrus fruits
- 3 copper wires, approximately 1' long each
- 2 copper pennies or copper nails
- 2 large galvanized zinc nails (at least 2" long)
- Battery-powered clock (one that uses a single battery, and does not also have an outlet cord)
- 2 alligator (electrical) clips or electrical tape
- AA battery
- Paper and pencil
- Permanent marker
Learn about Electricity, Electrons, and Batteries
- You and your child can look at the AA battery together to note that one end has a "+" sign on it, and the other end has a "-" sign on it. These are known as positive and negative terminals. For further exploration, open up the clock's battery compartment and note that it, too, has positive and negative terminals.
- Tiny particles of electricity known as electrons can travel between a negative and positive terminal, if there is something connecting them that allows those electrons to flow between them. That connection is known as a conductor, and some materials, including zinc and copper, are much better conductors than other materials. When two different metals are used as terminals, the electrons push harder in one direction than the other, creating a current.
- In battery-powered devices, the battery itself makes electrons through a chemical reaction that occurs when a conductive circuit is created by putting the battery in between the positive and negative terminals in a battery compartment. The chemical reaction only takes place when the battery is in place.
- When conductive materials are placed in acidic solutions and juices (like those found in citrus fruits), it also creates a chemical reaction. That reaction breaks down the structure of the metal, releasing electrons into the solution.