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Lemon Light

Energy doesn't come just from burning gasoline, coal, or oil. It can also come from food, or more specifically the chemicals in food. In this activity, you will create a chemical reaction with the acid of a lemon and metal to create energy - enough to power a small light.

You Will Need:

  • One or more lemons. The more you have, the more energy you will create.
  • Zinc electrodes - a 3cm x 0.5cm piece of zinc metal, obtainable at local hardware stores. Alternatively, you can use a "galvanized" zinc-coated screw, nail, or penny made after 1982. (One per lemon)
  • Copper electrodes - similarly sized piece of copper metal. Alternatively, you can use a penny that was made before 1982. (One per lemon)
  • LED lightbulb
  • Copper wire – long enough to create a circuit from the zinc electrode to the lightbulb to the copper electrode. (One per lemon)

What to Do:

  1. Stick the zinc electrode into the lemon.  This is now the negative electrode.
  1. Stick the copper electrode on the opposite side so that it doesn’t touch the zinc electrode.  This is now the positive electrode.
  1. Repeat steps 1 & 2 for each lemon. Then connect the lemons together positive to negative (zinc to copper) with the copper wire.
  1. Connect the LED lightbulb to the two electrodes with copper wire.  The wire that sticks out of the flat side of the lightbulb should be connected to the negative side (zinc) of the chain of lemons and the wire that sticks out of the round side should be connected to the positive side (copper) of the chain of lemons.
  1. Check it out!

What's the Science?

The lemon battery is made up of two different metals, copper and zinc. Electric current enters and leaves the battery through these points. These "electrodes" are placed in an "electrolyte," the acid from the lemon, which is a solution that can conduct electricity.

A chemical reaction takes place between the acid and metal which causes electrons, which is what energy is made of, to gather toward the negative end of the electrodes and electrons to be lost on the positive side of the electrodes. A current flows from the negative to positive ends in order to push out the excess electrons and for those electrons to take the place of the electrons that were lost on the positive end.

This is enough energy to make the LED light to light up. Using other metals and acidic fruits can have differences in how well they create energy. Consider trying other methods out!

Experiment Demonstration

When you're visiting the California Science Center, be sure to check out the Transportation exhibit in Creative World to learn more about energy and fuel sources.

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