The orange created the greatest electric charge with 1 V of electricity.  I think it’s because in an orange the juices are mostly acidic and in order to make a battery you need acid so it makes sense that the orange would create the greatest electric charge.

Results:

Lemon: 0.5 V

Orange: 1 V

Lime: 0.25 V

Potato: 0.75 V

Questions:

1. If the bulb doesn’t glow you can find out if the electrons are flowing by connecting the wires to a voltmeter and if the needle in the voltmeter moves then you know that the electrons are flowing but there just isn’t enough of them to make the bulb glow.
2. What is causing the electrons to flow are the pieces of metal that we but into the fruit.  One piece of metal was copper and the other was a galvanized nail and since when placed into the fruit, which acts as an electrolyte, the copper becomes positive and the nail becomes negative which causes the electrons to flow.