To test which combinations of metals will produce the highest voltage in a fruit battery.

Fair Test:  I will keep this a fair test by only changing the variables (the fruit and metal combinations). I will use similar sized fruit and try to keep the surface area of each metal strip as similar as possible. I must also ensure the holes in the fruit are accurately 2 cm apart and parallel to increase the accuracy of my results.

Method:

• 8 cm long strips of magnesium, zinc, copper, lead and iron were cut out.
• Combinations of various metal strips were placed into a chosen fruit (lemon, apple, grapefruit or potato).
• A circuit was made using crocodile clips attached to the metal strips and a digital voltmeter.
• The voltage produced was observed on the digital voltmeter and recorded in a table.
• This process was repeated until the four fruits had been tested.

Diagram:

Results:

• Pb – lead
• Cu – copper
• Mg – magnesium
• Zn – zinc
• Fe – iron

Lemon

Apple

Grapefruit

Potato

Analysis of results:

Evaluation: I think that the experiment went quite well. It is hard to spot anomalous results on a bar graph, but I think my results are accurate, and fit my prediction. However I feel accuracy was limited and could have been improved if a set of 3 results was taken and average found. There was not enough time to do this though. Accuracy could also have been lacked due to the difficulty in cutting out equal sized strips. We had to use a steel nail of similar surface area because iron foil was unavailable. Fruits are also very unpredictable and vary. I think that we should have perhaps focused on one fruit, like the lemon, and used three different lemons to increase accuracy. This would perhaps be a more useful approach. I believe further investigations are needed to help fulfill the aim of the experiment. I think that acids and alkaline solutions should be used instead of fruits due to their unreliability. This will make the experiment quicker too. The outcome would be more predictable. The distance between the two metals in the fruit could be varied in further work to again test the voltages produced using different combinations of magnesium, iron, zinc, lead and copper. Other variables to be tested are the surface area of the metals and how that would affect the voltage produced, and also to oxidise or deoxidise.