A voltaic pile was the first battery made to constantly supply an electric current to a circuit. It was invented by Alessandro Volta in 1800.
He alternately piled cloth soaked in brine, copper and zinc discs. One stack of copper, zinc and cloth disk is called a cell. One cell contains approximately 1.1 volts; the more cells in a pile the higher the voltage. When the top and the bottom of the pile are connected by a wire, electric current runs through the whole pile.
Making a Voltaic Pile
Making a voltaic pile at home is simple.
Materials needed:
- Coins
- Aluminum foil
- Cardboard
- Cider vinegar
- Salt
- Saucer
- Copper wire
- Masking tape
- Light bulb
Steps:
- Cut the aluminum foil and cardboard into circles. Set the cut outs aside.
- Make an acid mixture by mixing cider vinegar and salt in a saucer.
- Soak the cut out cardboard in the acid mixture.
- Tape the copper wire to one of the cut out aluminum foils.
- Alternately stack the aluminum foil, cardboard and coin.
- On the last coin, tape another copper wire.
- The other end of the copper wire is then attached to a light bulb.
- And presto! The light bulb is illuminated.
Explaining the experiment
It is important to know that to have an electric current it needs movement of electrons in an electrolyte. There are two things needed: electrons and movement of electrons.
In this experiment the acid mixture acts as the electrolyte containing ions. The ions will react to the two different metals, in this case the coin and foil, and form electrons.
Now you have electrons, the second thing needed would be movement of the electrons.
The two metals (the coin and the aluminum foil) react differently. One metal attracts electrons, and so becomes negatively charged or the cathode, in this case the coin. The other metal loses electrons, and so becomes positively charged or the anode, in this case the aluminum foil. The different charges allow electrons to move creating an electric current.
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