We looked at circuits,
dismantled an old laptop,
made an electrical musical instrument
and looked at the electrical current in fruit
This one really surprised the girls - they expected the lemon to have the highest result but they were in order....
Apple the lowest with Kiwi being the highest !
this link explains how to set it up and why it works
A wet cell consists of a negative electrode; a positive electrode and an electrolyte, which conducts ions (atoms with an electric charge). In this science fair project copper and zinc metals will be used as the electrodes and the citric acid found in fresh fruit is the electrolyte. The chemistry behind the fruit cell is that zinc is more reactive than copper which means zinc loses electrons more easily than copper. As a result, oxidation occurs at the zinc metal strip and zinc metal loses electrons to become zinc ions. The electrons then flow from the zinc strip to the copper strip through an external circuit. At the copper strip, reduction occurs the hydrogen ions in the fruit's critic acid juice accept these electrons to form hydrogen gas; this explains why the investigator may observe bubbling of gas produced at the copper strip when the two metals are connected by a wire.