Building a working battery from scratch is within the reach of everyone. In fact, with a few basic items, you can make a working replica of the world’s first modern battery, invented by Alessandro Volta way back in 1799.
Put coins into a bowl of vinegar, mixed with a little salt. Leave for a few minutes, then rub dry until shiny.
Using a 2p as a template, cut out nine card circles. Make nine foil circles – cut these a bit smaller. Soak the card circles in vinegar, mixed with a little salt.
Build up a stack in this order: coin, damp card circle, foil disc. Continue until you run out of coins. Make sure foil layers do not touch.
Take a wire and stick one end to the top coin surface. Take another wire and stick an end to the bottom coin surface. Add tape to secure the battery.
Connect the free ends of the wires to your LED.
What’s going on?
The same basic ‘electrochemical’ processes take place inside all batteries, including the one you’ve just made. All atoms are surrounded by a cloud of negatively charged particles called electrons. In the coin battery, each aluminium foil circle reacts with the acidic vinegar electrolyte to generate aluminium hydroxide on its surface along with an abundance of electrons. The excess electrons repel one another and escape from the metal along the wire. The moving electrons pass through the LED and round the circuit to the copper in the coins. The copper then serves to let the negative charge back into the electrolyte, thus replenishing the electrolyte and letting the reaction continue.
The oxygen that is dissolved in the electrolyte takes part in the electron transfer, and when it has been used up the electricity will stop flowing. Because there isn’t a lot of electrolyte in your coin battery, it will quickly run out – so use your LED wisely!
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