How to Make a Potato Clock Science Project

One of the fun ways to test you science knowledge is to make projects that work on electricity. You can think of making a potato clock for such projects. Read on to find how to make a potato clock science project through this article.
The phosphoric acid present in potatoes can be put to good used by turning them into batteries for running clocks. The project of potato clock is very simple to make; materials needed for this project are easily accessible. The potato battery is capable of supporting only small power loads. So don't expect to light up a lamp with such a battery. You can make use of a series of potatoes for lighting up lamps.

Potato Clock Science Project

The potato clock is one of the simplest projects that children can think of for their school science fair. It is generally observed that science projects involving the use of electricity interest the kids. Children can create something that actually works through such projects.

Materials Needed
  • Two large-sized potatoes
  • Copper wire (2 inch in length)
  • Steel wool
  • Galvanized nail (zinc coated)
  • Alligator clips
  • Jumper wire
  • LED Clock Unit
  • Voltmeter
  • In this science fair project, potatoes work as galvanized cells and operate the clock. Flow of electrons that takes place in the phosphoric acid present in potatoes is responsible for development of electric charge.
  • Make use of a clock that runs on a voltage between 1-2 V.
  • The copper wire and galvanized nail used to make a potato battery should have a shiny and receptive surface. Only a receptive and reactive surface of these metals can conduct electricity. In order to make it shiny, scuff the surface of metals.
  • Now insert the galvanized nails and copper wires into the potatoes; push them about one inch deep into the potato.
  • There is a battery compartment in clocks. Remove the battery present in this compartment and connect jumper wires to its terminals. Connect the copper wire of one potato and positive terminal of clock by means of a jumper wire; take another jumper wire and connect galvanized nail of second potato to the negative terminal of clock.
  • Now connect the remaining i.e. open ends of the potatoes to each other. These ends will be the galvanized nail of first potato and copper wire of the second.
  • Use of alligator clips allows jumper wires to fit to the electrodes in proper manner.
How Does the Potato Clock Work?

A potato clock operates by means of electrical energy supplied by potatoes. Chemical reactions that take place in potatoes are known to generate this electrical charge. So, how is the charge actually generated. The following explanation should prove to be useful. Phosphoric acid acts as an electrolyte in the generation of electric current. Reaction of the zinc (galvanized nail) and copper surface with this electrolyte generates the required current. Zinc reacts with phosphoric acid to release electrons. Since, the zinc molecules lose electrons during this reaction, they become positively charged and get dispersed into the electrolyte. Copper molecules have a greater tendency to attract electrons in comparison to zinc. By attracting electrons, the copper molecules turn into anions (negatively charged ions). Now, the excess electrons present on the surface of copper molecules are attracted by hydrogen ions (they have greater capacity to pull electrons) present in the electrolyte solution. So, the copper molecules again go in search of electrons. All these processes allow electrons to flow freely in the electrolyte solutions; result of this activity is the generation of electric current. You can also make similar electricity projects by using fruits like lemon, orange, apple, etc.

Sometimes, only two potatoes don't generate enough charge for running a clock. In such cases, two or more potatoes can be added to the series. Hope you have understood how to make a potato clock science project through instructions presented above.
By Shashank Nakate
Published: 6/17/2011
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