Batteries consists of two metals suspended in a acidic solution. In our case, the lemon juice inside the lemon is the acid, since there is citric acid inside. The two metals we used were copper and zinc. As we connected the wires and the metals together, we made a circuit. The zinc had a negative charge, and the copper, a positive charge, so it allowed the electrons to pass through and into the phone. A lot of people think the electricity is caused by the lemon, but it is actually caused by the chemical reaction in the zinc.