It’s easy to make a simple dry-cell battery to demonstrate the nature of generating electricity. You don’t need any special equipment or potentially harmful acid liquids, just spare change and salt water.
Soak the coffee filter in a solution of 1 tablespoon salt to 1 cup warm water.
Gently wring out most of the water. Tear the filter paper into pieces slightly larger than a penny.
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Stack coins with salt-water-soaked filter paper between them. Start with a penny on the bottom and alternate penny, dime, penny, dime, ending with a dime. Do not place paper under the bottom penny or on top of the top dime.
Attach one alligator clip to the bottom penny and one side of the galvanometer. Place the piece of cardboard under the stack of coins on the opposite side of the alligator clip to level the stack and keep it from toppling over. Attach the other alligator clip to the top dime and to the other side of the galvanometer. If you don’t have or can’t find a galvanometer, touch the other ends of both alligator clips to the base of the light bulb to complete the circuit and light the bulb.
Observe the indicator needle on the galvanometer as it measures the electricity generated by your homemade dry-cell battery.
It is necessary to use pennies minted before 1982 because they contain enough copper to create electricity; pennies minted after 1982 are copper-plated and do not contain enough copper to create electricity.
Ensure that the paper filter prevents the pennies and dimes from touching each other or your dry cell battery will not work.