Kids, how would you like to make electricity with a lemon? You'll need a lemon, a galvanometer, 2 stiff copper wires, a large paper clip, and scissors.

Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

If there is any insulation on the ends of the wire, have an adult strip it off. Untwist the paper clip and twist the end of one of wires around it. Squeeze and roll the lemon to loosen the pulp inside. Make two small cuts in the skin of the lemon an inch or so apart. Insert the bare wire and the paper clip through these cuts into the juicy part. The two wires should be close but not touching. Connect the free ends of the two wires to the terminals of the meter.

Now watch the meter move! What's happening here? Electrochemistry causes the two different metals (the copper wire and the iron clip) in the acid (lemon juice) to draw electrons away from one wire towards the other. They flow out fo the lemon through one wire, go through the meter and then enter the lemon by the other wire.

You can even try to make your own galvanometer (an instrument designed to detect electrical currents) if one isn't available to you. You'll need a compass, 15 feet of bell wire (hardware store), and a small rectangular cardboard tray. Place the compass in the cardboard tray. Scrape off 1/2" of insulation from each end of the bell wire. Starting 6" from one end, wind the wire tightly around the box, circling it at least two dozen times. Leave another 6" of wire free on the other end of the tray. Rest your homemade galvanometer on the table horizontally and turn it until the compass needle is parallel to the coil of wire. Use these bell wire ends to attach to your lemon and paper clip.

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Kathleen Carrado Gregar, PhD, Argonne National Labs 
[email protected]
March 1997

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Reference: "Simple Science Experiments with Everyday Materials" by M. Mandell, NY: Sterling Publ., 1990, p. 58.