According to the California Science Center, lemon juice can both conduct and produce electricity. Lemon juice contains citric acid, which is a strong electrolyte. The electrolytes in lemon produce electricity by allowing two metals to react with each other.
The acid in the lemon is dissolved into positive and negative ions in its natural water. When rods of copper and zinc are placed in the lemon, a chemical reaction takes place. Within the lemon, electrons flow from the rod of copper to the rod of zinc, turning the zinc into a negative electrode and the copper into a positive electrode. A single lemon can generate about 7/10 of a volt of electricity.