The apple battery

The electrical power supplied by the battery is so low that only one LED can be made to light up. To be able to see the light better, the diode is placed in a film canister. To do this, drill a small hole in the bottom of the film can and push the two legs of the light-emitting diode through to the outside (see photo). Grate the apple and distribute the pulp into the three remaining cans (the cans should be filled to the brim). Place one zinc and one charcoal stick in each film can. Now connect the rods with the wire as shown in the photo. The circuit is closed via the light-emitting diode (carbon rod of the first can and zinc rod of the third can). The LED only lights up if the polarity of the battery is correct: The long leg of the diode must be connected to the negative pole of the battery, which is the carbon rod. The short leg of the diode is connected to the zinc rod, which is the positive pole of the battery.

• a kitchen grater,
• a sour apple,
• 4 film cans,
• 3 charcoal sticks,
• 3 zinc rods or strips,
• a red light-emitting diode ,
• 4 copper wires (2 x 10 cm and 2 x 20 cm) or 4 experiment cables with crocodile clips,

The diode lights up. We have made electric current flow.

The experiment should be carried out very carefully. The zinc and charcoal sticks in each can must not touch each other! The zinc strips or rods can be obtained from locksmiths (metalworking companies) and the carbon sticks from specialist stores for drawing and painting supplies. A little tip: If you can't find anything in the shops, you can also dismantle an empty flashlight battery. Inside you will find a carbon rod and a zinc cup. Caution! Only use zinc-carbon batteries, not alkaline batteries or rechargeable batteries. The batteries also contain toxic and corrosive material. Gloves and eye protection! Do not eat or drink! Keep away from food.

What is technically behind the experiment

This simple experiment shows how a battery is constructed in principle. Although there are different types of batteries, the principle is always the same. Charge separation takes place through a chemical process. There are two electrical poles, a positive and a negative pole, which are located in an electrolyte (acid or alkaline solution). If the poles of the battery are connected to each other via a cable, electrons in the cable move from the negative to the positive pole. (Important: Not only do electrons migrate out of the battery, but the electrons in the cable also start to move. The battery provides the "impetus", so to speak). A corresponding electron migration from the positive to the negative pole takes place in the battery. During this process, the materials in the battery change. This is why a battery only has a limited service life. In order to generate sufficiently high voltages, three batteries are practically connected in series in this experiment. Even a flat battery is nothing more than three individual batteries connected in series.

What the experiment has to do with everyday life

It is a simple representation of batteries that we find in everyday life (in flashlights, toys, remote controls, etc.).

The experiment can also be carried out with vinegar instead of apple puree.

Bozena Dombrowski