Dr. Rosler (a.k.a. Science Mom) taught the children about Leonardo Da Vinci during our science class last week. We learned that he lived a long time ago in Italy. He was an artist and an inventor who loved science and nature. Did you know that Da Vinci wrote with lemon juice so people wouldn't be able to see what he wrote? To read the message, the paper would have to be held over a candle. The heat from the flame would oxidize the lemon juice and turn it brown revealing the message (the first attempts at invisible ink?).
To begin the experiment of making a battery using a lemon, Dr. Rosler cut two small slits in each lemon about 1/2 inch apart. The children were given a penny, a dime and a small piece of sandpaper to clean off the coins. Once cleaned, the penny and dime were pushed halfway into these two slits. The children were then asked to touch both the penny and the dime at the same time with their tongue. Did they feel anything? Maybe a tingling? Not sure if the children felt anything... but they did have fun making lemonade afterwards!
How does this work? The acid in the lemon reacts differently with each of the two different metals in the coins. One of the coins contains positive electric charges, while the other contains negative electric charges. These charges create current, which will flow if the battery circuit is complete. Your tongue acts like a wire and conducts the charges, making the circuit complete. The complete electric circuit causes a small amount of electricity to flow, which causes the sensation on your tongue.
Thank you Dr. Rosler... we learn so much and have such fun with you on Thursdays!
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