Fruit Batteries


  • There is little practical use for such batteries because they provide so little current and voltage, but they are interesting to play with.
  • Acidic fruits and vegetables can generate an electrical current if two electrodes made of different metals (such as zinc and copper) are jammed into them:
    • The chemical reactions between the metals and the acids within the fruits and vegetables result in the generation of current.
      • The fruit juice in this case is the electrolyte and is used up during the reaction.
      • As such it is necessary to clean the metal electrodes with iron wool, or other such abrasive materials before inserting them deep into the flesh of the fruits and vegetables.
        • But the electrodes must not touch each other else a short circuit will occur within the fruits.
      • This reaction releases hydrogen gas.
  • The greater the amount of juice in the fruit or vegetable the greater the capacity.
  • The greater the contact area between the electrodes and the fruit’s juice the greater the voltage:
    • Because there is a higher rate of reaction.
  • The lower the pH of the electrolyte the higher the voltage generated:
    • Because there is a higher rate of reaction due to the larger concentration of hydrogen ions.
  • The greater the difference in reactivity between the two electrodes the greater the voltage generated:
    • Because there is a higher rate of reaction.
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