Share facts or photos of intriguing scientific phenomena.

Science Fair Projects: Learn How to Make a Clock Using a Potato!

Potato Clock Project for a Science Fair
Looking for an easy project for the upcoming science fair? Why not try the simple potato clock?
Puja Lalwani
Last Updated: Dec 10, 2017
The idea of a clock working on the power generated by a potato may seem bizarre, but it is a fact. Potatoes do have the capacity to generate electricity. The potato clock was invented in the year 1983 by William Borst, while helping his daughter with a project, where he recreated a demonstration he had seen during high school.
This has now become a popular science fair project that is now conducted by many students. The potato clock is a perfect project at the elementary level, that introduces students to the chemical reactions that result in power generation. If you are looking for an elementary science fair project, and are confused about what to take up, take a look at one of the most simple, yet fascinating science fair projects, the potato clock.
How to Make a Potato Clock
» Materials Required
  • Baking potatoes, 2
  • Galvanized (zinc coated) nails, 2
  • Copper wire, 2 short lengths
  • Jumper wires with alligator clips (on each end), 3
  • LED clock, low voltage, 1 (1.5 Volts - 2 Volts)
» Method
  1. Firstly, assign a number to each of the potatoes, as 1 and 2.
  2. Remove the battery from the clock. Keep in mind the positive (+) and negative (-) terminal points at the place of the battery.
  3. Insert one nail each in both the potatoes.
  4. Insert one length of copper wire each, in both potatoes, ensuring that they are placed away from the nails at a maximum possible distance.
  5. With one alligator clip, connect the copper wire in potato 1, to the positive terminal in the clock.
  6. With another alligator clip, connect the galvanized nail inserted in potato 2, to the negative terminal in the clock.
  7. With the third alligator clip, connect the nail in potato 1 to the copper wire in potato 2.
  8. The clock is now ready to be set and used.

Isn't it remarkable how something you eat with your regular burger can actually be used to power a clock?
How a Potato Clock Works
You have completed the project, but it is important that you understand its functioning. A potato contains an electromotive force, that has the power to move electric current. As such, it is an electrochemical battery, that stores chemical energy, which is then converted into electrical energy upon which different electronic objects function. The copper wire that is used in a potato battery, forces the electrons in the potato to move, thereby conducting low voltage electricity that makes the clock function. This entire chemical reaction is called the 'redox reaction.'
The redox reaction begins with one side of the battery losing electrons. The galvanized or zinc coated nail forms the anode or the positive terminal of the entire circuit. A reaction occurs between the phosphoric acid that is present in the potatoes with the zinc, which enables a release of electrons, i.e., 2 electrons from zinc. On the other hand, a reaction occurs between the phosphoric acid in the potato and the copper from the wire, which enables a reason of hydrogen ions, that receives the electrons. This functions as the cathode or the negative terminal of the circuit. As such, the anode loses electrons, while the cathode receives electrons. This entire chemical process results in the release of low volt electricity, which may be used to power a small clock, a computer fan, and even a light bulb.
An entire kit to conduct this experiment is now easily available in the market. However, making a potato clock from scratch will give you a better understanding of its functions, and will help you point out errors, if any, in the process.