Attribution: This is a cached copy of a third party project. Many of these sites are from 20 years ago and the majority are no longer running. We show only the first page of the project. We do not save all pages since copyright belongs to the third-party author.
POTATO POWER Purpose: In this activity, you will learn how to build a battery from potatoes. Materials: metal strips: copper, aluminum, zinc (galvanized steel) potatoes (at least 4) multimeter (volts, milliamps) wire clips steel wool (to clean the metal strips) Procedure: 1) Select two different metal strips and one potato. 2) Carefully place the metal strips into the potato. 3) Voltage: Set the meter to "DC Volts" and make sure the probes are plugged into the correct jacks. Also make sure that the scale is correct. All multimeters are different, but there should be a low scale, something like 2V, or 6V. 4) Attach wires from the meter's probes to the metal strips. 5) What does the meter read? 6) Current: Set the meter to "DC milliamps" and make sure the probes are plugged into the correct jacks. (Use the smallest setting on the multimeter.) 7) Attach wires from the meter's probes to the metal strips. 8) What does the meter read? (enter on the worksheet) (You may notice that the current decreases. As the current decreases, you are draining the battery. So take your measurement, then disconnect the wires.) Additional experiments: 1) Different metals: Now that you know how to make a potato battery, and know what voltage and current are, you will try to make a better battery. Some metals make better batteries than others. You will try to find the combination of metals that gives the most voltage and current. What combination of metals made the most voltage and current together? 2) Potatoes in Series Make another potato battery. Wire up the two potatoes in series. 3) Light the LEDs Now you are qualified to be a battery engineer! Your job is to design a more complicated potato battery to light two LEDs. Two LEDs need 1.6 volts and 1 milliamp to light brightly. The more current, the brighter the light. By putting potatoes in series and parallel, design a battery to do this: Now test your battery with the LEDs. LEDs are special lights that have a positive side (red wire) and negative side (black wire). Make sure you attach the positive side of your battery to the red wire and the negative side to the black wire. Notes The best combination of metals should be copper and zinc. The LEDs used here are special low current LEDs, rated for 1.8 V and 1 mA, but they will fire at about 1.6 V and .2 mA. One LED should fire with 2 potatoes in series (this barely produces the needed 1.6 V), but you may need 3. The 2 LED eyes are wired in parallel. Four potatoes should brightly light the eyes: two pairs in series, those pairs in parallel. The zinc used here is really galvanized steel, meaning zinc coated steel. Zinc is dissolved from the strips in the battery, so the metal strips have a finite lifetime.