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It isn’t magic, it's energy: learn how batteries work

Sometimes energy seems more like magic, which is why we have put together some summer experiments to show you that it’s all science. Science and a couple of lemons are all you need to build some batteries.

The holidays are here, so you have some time on your hands. And of course, any time is a good time to learn. That’s why Endesa is publishing some simple experiments that you can do at home with common materials that will reveal some of the secrets of energy. It isn’t magic, it's energy.

For this zingy experiment you’ll need a couple of lemons, four zinc coins, some cables and an LED light. It will show how batteries work and we’ll build an energy system to demonstrate it.

These simple, fun, household experiments will demonstrate the scientific principles that govern energy and make them easy to understand. Check out all our cool experiments in the Stories on our Instagram profile @EndesaClientes, Don't miss any of them. Follow us!

Today we are explaining our first experiment on our blog.

How to build a series electrical circuit with some original batteries made with lemons!

But you can’t generate electricity with lemons! Oh yes you can, and you know what? It isn’t magic, it’s energy!

Do the experiment yourself and share it with your friends and family. We'd love to see their reactions. Tag us on our Instagram and share it with us. If you do, you can enter a prize draw for an electric bicycle so you can travel sustainably this summer, thanks to Endesa.




  • Two lemons
  •  A knife
  • 4 metal nails
  • 4 copper coins (you need 1, 2 or 5 cent coins, which are made of steel and coated with a thin layer of copper)
  • 5 crocodile clips with cables
  • 1 LED diode

Step 1:

Cut the lemons into halves. Be careful! Make a cut or indentation to release some juice.

Step 2:

Insert a nail and a coin into each of the 4 lemon halves. Do this through the skin and rind. Position them so that they are facing each other, as far apart as possible.

Step 3:

Connect the coin in one lemon half with the nail in the other half using the alligator clips and cables.

Step 4:

Connect the remaining coin and nail to the LED light to create a series circuit and see how the LED lights up!

The trick

If this isn’t a magic trick, why does the LED light up when it is not connected to the mains electricity or to an energy storage system like a battery?

It is because of a chemical reaction. A normal battery, for example, produces a very similar chemical reaction. In a primary generator, a battery or our lemon, we need a negative pole (cathode) and a positive pole (anode).

Inside they contain a conductive solution or electrolyte, the more acidic the better, which is why lemons and their citric acid are perfect for this experiment. All the solution does is carry the electrical charge between the two poles.

The anode in the lemon is the zinc coin, which is where oxidation occurs.

The cathode in the lemon is the metal nail, which is where the hydrogen ions in the lemon juice are produced.

The process is simple: the zinc coin loses electrons which are gained by the hydrogen ions. As the electrons are exchanged, the zinc dissolves in the citric acid as positive ions. Hydrogen bubbles are created at the nail as it gains electrons that pass, in turn, into the wire. Once the zinc coating on the coins has completely dissolved, the battery is spent. The movement of the electrons generates the electric current.

In addition, the series circuit stops the flow of current from being interrupted.

When you set up this series circuit with four lemon batteries it generates and transmits enough energy to light the LED. Amazing, right?

If you don't have any lemons, or you're keeping them to make lemonade, don’t worry! Apples or potatoes also work for this experiment.

Don't forget to follow our Instagram profile to discover more It isn’t magic, it’s energy! experiments. There’s no need to get bored this summer!

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