Potatoes are good for mashing, baking, frying and also as low-power natural batteries. Insert two wires made of different metals such as copper, aluminum or zinc into either end of a potato. Touch the other ends of each wire to the base of a small voltage light bulb, which should light up. The reason for this is that the phosphoric acid within a potato reacts with the metal in the wires. The reaction causes electrons to be released, which travel along the wire, causing a small voltage and powering the bulb.
In the lemon battery experiment, copper and steel wires are inserted at either end of a lemon. As with the potato battery, the other ends of the wire are touched to a small bulb or even touched to your tongue, which causes a tingling sensation. The wires act as electrodes in the lemon with one creating electrons as it reacts with the lemon's acid, while the other takes on electrodes. When the free ends of the wires touch something to make a circuit, the excess electrons rush from one end to the other, creating a current and lighting the bulb.
Static electricity can also power a small bulb. This can be demonstrated by rubbing a comb against a woolen scarf vigorously for 30 seconds and then touching the comb to the base of a bulb. The static electricity stored in the comb causes the bulb to light up briefly. This also can be done with a balloon. The friction created from the rubbing causes electrons to be transferred to the comb. The comb, in turn, transfers the electrons to the bulb.
Certain bulbs can be lit by the presence of a powerful electric field. Using a self-exciting fluorescent bulb, the electric fields below power lines can be tested. It is definitely an experiment that requires adult supervision, so kids must be accompanied. While standing under a power line, hold the bulb as high as possible. It should pick up on the stray electric energy, which causes the gas in the bulbs to move around and glow.