 
 
TEACHER NOTES & ACTIVITIES
Clock ahead with potatoes
Strange but true - if you connect two potatoes with some wire and copper and zinc plates you can actually run a clock! If you prefer you could use the same concept to power a small light bulb!
 How to build a potato clock...
You will need:
- digital clock
- two potatoes
- wire
- zinc plate
- copper plate
You can pick up parts at an electronics shop
like Dick Smith.
Instructions:
- Check all the wires are securely connected (see diagram).
- Poke one copper plate and one zinc plate into each potato. The plates need
to be about two centimetres deep, and about two centimetres apart.
- Set the time on your clock - it should now be working.
How does it work?
Potatoes are full of a mineral called phosphoric acid, which reacts differently
with each of the metal plates (one copper and one zinc) in your potato.
Phosphoric acid dissolves the zinc plate, freeing electrons, which react with
the copper plate to form hydrogen gas. The potato acts as a superhighway of
electrons between the copper and zinc plates. This flow of electrons is the
electrical current that makes your clock work.
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