100 Days Project

Nanogirl: Star Science

Nanogirl wants to find 100 friends to do science experiments with her to prove that no matter who you are or what your education level, you can always have fun with science.

Day 25:

9 year old Caitlin makes a potato battery

Caitlin is a 9 year old who has created power from two potatoes!  She has created so much power that she can run a clock from them - pretty impressive!

Caitlin took two potatoes and stuck a galvanised nail into each one, then she pushed a copper nail on the opposite side of each potato.  She then connected one of the copper nails to the positive (+) side of the battery holder metal using a piece of wire.  To make sure the wire stayed in place, Caitlin stuck the wire and the nail together with sticky tape.  Now Caitlin took the other potato and connected the galvanised nail to the negative (-) side of the battery holder metal using more tape.  To complete the circuit, Cailtin then hooked together the unconnected nails from each potato using another wire, so that now all of the nails are connected either to each other or to the clock.  Once the circuit is complete, the clock has power and starts working!

How on earth can you create electricity from a potato?

Electricity is the result of a chemical reaction and we have all the incredients for a reaction with copper, zinc and acid.  The galvanised nail is coated with zinc which is negatively charged and the potato is filled with a mild acid called phosphoric acid (H3PO4).  The acid frees some of the electrons in the galvanised nail and they are drawn to the positively charged copper causing the electrons to flow through the wire and complete the electrical circuit.  By placing the clock in the middle of the circuit you can prove the electricity is flowing by seeing that it is powered up! 

There is the added bonus of being able to eat most of yor experiment when you are done, the question is mashed, boiled or baked?