What To Do
SAFETY – Get an adult to help with this experiment and, due to the process that generates the electricity, a little hydrogen gas can be produced therefore, do not perform this experiment near any naked flames.
Note : Potatoes (and lemons for that matter) can be used to power electronic devices. Each potato – depending on condition and type – will generate about 0.5v so if you want to power something that requires more power than that, just add more potatoes.
To get electricity from potatoes you will need (obviously) some potatoes, zinc nails, copper nails, some wire and an LED bulb (this can be any time of bulb in but lower voltage required of LEDs makes them more suited to this activity. With my setup, four potatoes worked but it took five potatoes to brightly illuminate the LED bulb.
Line the potatoes up and place one copper nail and one zinc nail into the first potato and position them so they are not touching. Do the same with 3 other potatoes. Cut three lengths of wire (about 15cm each will be plenty) and strip the plastic protective sheath off each end. Connect one end of a piece of wire to a copper nail and the other end of the same wire to the zinc nail on the next potato. Hook all the potatoes up so a zinc nail on one, connects to a copper nail on another. Once you have used up the three wires then you should have two potatoes with a zinc nail on one potato and a copper nail on another not connected to anything.
Cut two more lengths of wire and strip the ends off the plastic sheath. Connect one of the nails to one wire on the LED and connect the other nail to the other wire on the LED. If it does not light up then swap the wires around and you should now have an LED light gently glowing under the power of potatoes.
The zinc in the nail reacts with the acid inside the potato which causes electrons to flow between the zinc and copper nail just like a battery.