Variations

Potatoes, apples or any other fruit or vegetable containing acidity or other
electrolyte can be used, but lemons are preferred because of their higher
acidity. Other non rusty metal combinations (such as magnesium-copper) are
more effective: for example, using a magnesium strip instead of zinc
increases the voltage from 1.1 V with zinc to 1.6 V with magnesium. (The
exact voltage varies depending on the lemons.) However, zinc and copper are
usually preferred because they are reasonably safe and easy to obtain.