Fruits and vegetables contain important vitamins and minerals human bodies need to survive and maintain themselves properly. However, interestingly, these same fruits and vegetables also contain a large amount of water and, thus, can in some cases conduct electricity well. Other ingredients such as citric acid and ascorbic acid increase the conductivity, and in some cases, the acidic content is high enough to create voltage that can power small electronics.

Potatoes, onions, and tomatoes conduct electricity quite well. Tomatoes (not vegetables, strictly-speaking ) are good conductors in the vegetable category, as they have the highest acidity level. Scientists have show potatoes work very well as batteries. Acids make ions, charged particles when placed in a solution like, water, which many types of fruits and vegetables contain in abundance.

Citrus fruits work as excellent conductors due, again, to their high acidity level and the presence of water within them. Some notable examples of good conductors include:

• apples
  
• grapefruit
  
• oranges
  
• lemons
  
• limes

When a fruit or vegetable is connected with electrodes in a circuit, the fruit or vegetable serves as the battery to complete the circuit. Some of them can even power small light bulbs for a time. Some researchers have shown that boiling a potato for around eight minutes can increase its capacity as a battery 10 times compared to a raw potato. Sandwiching a quarter of a boiled potato between a copper cathode and a zinc anode can power a lightbulb for 40 days.

Perhaps not surprisingly, several pieces of fruit or vegetables connected in a parallel circuit creates a higher current. If the fruit or vegetables are connected in a series arrangement, the voltage is increased. This, in turn, can be used to power increasingly complex machines and electronics like a wristwatch.