Study of the characteristics of lemon as a current source. A lemon battery and a method for making it How to light a light bulb using a lemon

Natural batteries of electrical energy, a battery made from fruits - is this possible? Let's try to sort this issue out in our laboratory.

It should be noted that this experiment is good for its simplicity and clarity. It can be used both for a school science project (especially by adding a theoretical section), and as a form of entertainment, making a good presentation, for example, for friends. This experience is great if you just decide to spend quality time with your child – both fun and educational!

In the previous article about we touched a little on the history of the creation of the battery, found out where the electricity comes from in it, and looked at the processes occurring in the galvanic cell. And an incredibly useful method of understanding the world around us called “What’s inside?” helped us see what a battery is made of. True, we had to break several galvanic cells, but in this article, I promise, we won’t break anything. Just create!

What do we need for this? As we have already found out, any galvanic cell consists of electrodes and an electrolyte. Following tradition, we will not use any exotic or hard-to-find materials. If you want to repeat the experiment, you will need the following:

• Vegetables or fruits that you have on hand. Just don’t tell those around you what you need them for, otherwise the next time you want, say, an orange, they won’t give you one - they’ll say that you’re going to transfer food again :) They will play the role of electrolyte in our batch of batteries (or rather , the fruit juice they contain, which, thanks to fruit acids, acts as an ion exchange medium).
• Iron and galvanized nails. If you don't have galvanized nails, you can use pieces of galvanized sheet metal. If, after the previous article on the design of batteries, you still have a zinc case, it’s time to take it out of the treasured box. As you understand, all this will act as electrodes.
• Several wires. I took several cores from a multicore twisted pair cable. We need wires in order to organize an electrical circuit - the very bridge along which electrons run from one electrode to another.
• And of course, we will need a current consumer - why do we need electricity if we have nowhere to spend it. As a consumer, you should use something low-power: for example, a calculator or an LED. You should not take anything more powerful, for example, an incandescent lamp. Although, the last remark can be neglected if you have a truck with lemons parked in front of your house.

Let's lay out the components on our laboratory table.

We strip the ends of the wires from insulation.

We begin to immerse the electrodes in the electrolyte. Well, to put it simply, stick nails and plates into prepared food supplies. First one electrode...

... and then another.

We attach wires to the ends of the electrodes.

The galvanic cell is ready! Half a lemon shows almost half a volt.

Having completed all the above procedures with an apple, we see that a galvanic cell from this fruit produces a similar voltage.

Orange provides similar tension.

But the onion gave a surprise. It turned out to be a high-voltage battery :)

Now let's see what all this fruit-electric brethren of ours is capable of. Of course, each of these elements is capable of little. Maybe just demonstrate with a voltmeter that they actually produce electricity. Much more effective would be a demonstration of the operation of current consumers from our fruit batteries. As I already noted, the voltage produced by a separate fruit galvanic cell will not be enough to power even low-power current consumers. Therefore, we need to increase the voltage. This can be achieved by connecting several galvanic cells in a series circuit, i.e. like this:

After connecting all our galvanic cells into a battery, we already get quite a solid voltage.

Let's try to connect the LED (when connecting, you must observe the polarity)... It's lit!!!

Even the old calculator, which I stopped considering working a long time ago, started working from a fruit battery!

Well, the experience was a success! As you can see, a fruit battery is quite possible. Of course, it cannot be considered as a serious source of power. But as an excellent visual material about the nature of electricity, which for the uninitiated may even look a little mystical - quite!

Good luck with your experiments!

MBOU "Secondary school No. 6 of Yurga"

Section: The world of my interests.

Fruit battery.

MBOU Secondary School No. 6, 4th grade student

Head: Belonosova T.V.

Yurga

2015

l. Introduction.

ll. Main part.

How does the battery work?

Practical use of the battery To.

lll. Conclusion.

lV. Bibliography.

V. Application.

l. Introduction.

M
This job was born out of a passion for books and a desire to make crafts. I first read about the non-traditional use of fruits in Nikolai Nosov’s book. According to the writer's plan, Shorty Vintik and Shpuntik, who lived in the Flower City, created a car that ran on soda with syrup.

And then I thought, maybe fruits also keep some secrets.

I wanted to learn as much as possible about the unusual properties of fruits. Scientists say that if the power goes out at your home, you can light your home for a while using lemons.

The purpose of my research:

Generating electric current from fruits.

You can see the tasks on the slide.

1. Familiarize yourself with the principle of battery operation.

2. Create fruit batteries.

3. Experimentally determine the voltage of such batteries.

4. Try to light a light bulb using a fruit battery.

Subject of study: receiving electric current.

Object of study: fruit batteries.

G
hypothesis:

Are fruits a source of electric current? Is it possible to make a battery out of fruit?

ll. Main part.

How does the battery work?

First, let's figure out what electric current is. Electric current is the movement of electrically charged particles. I decided to find out how a regular battery works. I didn’t disassemble the battery myself, I used the encyclopedia. Any battery or accumulator is two metal plates placed in a special chemical substance - an electrolyte. One plate is connected to the “+” terminal, the other to the “-” terminal.

Battery is a convenient storage of electricity that can be used to power portable devices. Some batteries are single use, others can be recharged. Batteries come in a variety of shapes and sizes. Some are small, like a tablet. Some are the size of a refrigerator. But they all work on the same principle. They create an electrical charge as a result of a reaction between two chemicals, during which electrons are transferred from one of them to the other.

The electrodes are zinc (galvanized plate) and copper (copper wire), and the electrolyte is a solution of salts and acids. Two metals immersed in a solution enter into a chemical reaction and an electric current is generated.

The first source of electric current was invented by accident, at the end of the 17th century, by the Italian scientist Luigi Galvani (in fact, the goal of Galvani’s experiments was not to search for new sources of energy, but to study the reaction of experimental animals to various external influences). The phenomenon of the generation and flow of current was discovered when strips of two different metals were attached to the frog's leg muscle.

Galvani's experiments became the basis for the research of another Italian scientist, Alessandro Volta. 200 years ago he formulated the main idea of ​​the invention.

The very first battery, invented 200 years ago, was powered by fruit juice.

Alessandro Volta made a discovery in 1800 by assembling a simple device from two metal plates (zinc and copper) and a leather spacer between them soaked in lemon juice.

Alessandro Volta discovered that a potential difference arises between the plates. The unit of voltage measurement was named after this scientist, and his fruit energy source became the progenitor of all modern batteries, which are now called galvanic cells in honor of Luigi Galvani.

I saw a photo on the Internet showing a device that you can assemble with your own hands. This is an electronic watch that uses fruit instead of a battery.

I conducted a survey among students in my class to find out what they know about batteries and the existence of a fruit battery.

What's in the battery?

Based on the results of the questionnaire, I can conclude that: the guys know what is contained inside the battery and how it works. And the guys heard about the fruit battery. (Fig. 1)

Fruit juice in its composition is a weak acid, so if you insert 2 electrodes into the fruit: one copper and the other zinc, then a weak current will flow between the electrodes, sufficient to power the watch. But I’m not used to taking his word for it, so I decided to check personally whether it’s true or not.

Experiment to create batteries.

To create fruit batteries I needed:

M materials:

Galvanized plate

A multimeter is a device for measuring current and voltage.

4.Fruits.

I start measuring the current in the fruit.

With the help of my dad, I made galvanic cells from a pear, an apple and a lemon. Each element was measured with a multimeter. (Fig.2)

We were surprised that lemon, pears and apples provide electricity! I entered the voltage measurement results into a table. (Fig.3)

I found out that a regular AA battery produces 1.5 Volts.

So, The hypothesis was confirmed: different fruits give different current strengths.

V. Application.

Picture 1.

Questionnaire.

What's in the battery?

All the guys answered this question - yes.

Are there fruit batteries?

Figure 2.

We take a pear, insert a copper wire on one side, and a zinc plate on the other.

The battery is ready, measure the voltage.

We take an apple, insert a copper wire on one side, and a zinc plate on the other. The battery is ready, measure the voltage.

We take a lemon, insert a copper wire on one side, and a zinc plate on the other. The battery is ready, measure the voltage.

An ordinary AA battery provides 1.5 Volts.

Figure 3.

Voltage measurement results.

Fruits

Voltage, V

Pear

0.90

Apple

0.87

Lemon

0.90

Figure 4.

We took a small LED light bulb. We connected it to the lemon contacts.

My blue LED starts to glow!

Many schoolchildren in chemistry, physics or labor lessons were lucky enough to make a battery out of a lemon. This sounds strange, because everyone is used to seeing standard-type batteries. But the source of energy from the fruit is something unusual!

How to make a battery from a lemon?

In fact, you can build such an installation from any fruit. The only difference will be in tension. Lemon has the advantage of containing citric acid. It is capable of generating greater electrical current.

Here's what you'll need to create a lemon battery:

1. Lemon – 1-2 pieces.
2. Copper wire in the amount of 1 piece. For a large-scale experiment, you can take more. If not, you can use a coin.
3. Zinc plate. It can be a regular metal bolt, screw or wire.
4. Multimeter or voltage tester.
5. Light-emitting diode. It will allow you to clearly record that there is current.

As you can see, the manufacture of this battery is based on only three things.

Step #1.

Take a lemon and remember it a little. You can also wash and wipe if you wish. Although it's not that important.

Step #2.

Place a copper conductor at a shallow depth of up to 2 cm and a metal conductor not far from it.

Connect the wires to the protruding rods.

Test with a multimeter how many volts this installation produces.

As a result, 0.91 volts!

Assemble the second lemon battery and connect them in series. Or plug in another copper and metal wire. Then connect them diagonally to each other.

The fact is that the LED will not light from one battery, so you will need a second one.

Thus, the lemon battery can consistently produce electric current.

Explanation: The operation of such a battery is based on the interaction of two conductors of opposite metals. Once they are placed in the lemon, they are surrounded by a citric acid environment. This substance serves as an electrolyte. That is, a chemical reaction begins to flow and ions move, releasing energy.

It is best to use copper wire in place of the coin.

Light a light bulb with... a lemon!

Complexity:

Danger:

Do this experiment at home

Safety

Before starting the experiment, put on protective gloves and goggles.

Conduct the experiment on a tray.

General safety rules

• Do not allow chemicals to come into contact with your eyes or mouth.
• Keep people away from the experiment site without protective glasses, as well as small children and animals.
• Keep the experimental kit out of the reach of children under 12 years of age.
• Wash or clean all equipment and fixtures after use.
• Ensure that all reagent containers are tightly closed and stored properly after use.
• Make sure all disposable containers are disposed of correctly.
• Use only the equipment and reagents provided in the kit or recommended by current instructions.
• If you have used a food container or glassware for experiments, throw it away immediately. They are no longer suitable for storing food.

First aid information

• If reagents come into contact with your eyes, rinse thoroughly with water, keeping the eye open if necessary. Contact your doctor immediately.
• If swallowed, rinse mouth with water and drink some clean water. Do not induce vomiting. Contact your doctor immediately.
• If reagents are inhaled, remove the victim to fresh air.
• In case of skin contact or burns, flush the affected area with plenty of water for 10 minutes or longer.
• If in doubt, consult a doctor immediately. Take the chemical reagent and its container with you.
• In case of injury, always seek medical attention.

• Improper use of chemicals can cause injury and damage to health. Carry out only the experiments specified in the instructions.
• This set of experiences is intended for children 12 years and older only.
• Children's abilities vary significantly even within age groups. Therefore, parents conducting experiments with their children should use their own discretion to decide which experiments are appropriate and safe for their children.
• Parents should discuss safety rules with their child or children before experimenting. Particular attention should be paid to the safe handling of acids, alkalis and flammable liquids.
• Before starting experiments, clear the experiment site of objects that may interfere with you. Avoid storing food near the test site. The testing area should be well ventilated and close to a tap or other water source. To conduct experiments you will need a stable table.
• Substances in disposable packaging must be used completely or disposed of after one experiment, i.e. after opening the package.

FAQ

The LED is not lit. What to do?

First, make sure that the slices in the lemon are not touching each other.

Secondly, check the quality of the connection between the crocodile clips and the metal plates.

Thirdly, make sure that the LED is connected correctly: the black crocodile is attached to the short “leg”, the red one to the long one. In this case, the crocodiles should not touch the other “leg”, otherwise the circuit will close!

The juice near the magnesium plate hisses. This is fine?

Everything is fine. Magnesium is a reactive metal and reacts with citric acid to form magnesium citrate and release hydrogen.

Other experiments

Step-by-step instruction

1. Take 2 magnesium plates from the jar labeled “Mg”.
2. Prepare 2 alligator clips: 1 black and 1 white. Connect the magnesium plates to the black and white crocodiles.
3. Take 2 copper plates from the jar labeled "Cu".
4. Connect the copper strip to the free end of the white crocodile. Connect the copper plate to the red crocodile.
5. Cut the lemon in half. Insert copper and magnesium strips into one half of the lemon at a short distance from each other (about 1 cm). Repeat with the remaining two slices, using the other lemon half. Make sure the plates are not touching.
6. Take the LED. Connect the free end of the red crocodile to the long leg of the LED. Connect the free end of the black crocodile to the short leg of the LED. The LED will light up!

Disposal

Dispose of solid waste from the experiment along with household waste. Drain the solutions into the sink and then rinse thoroughly with water.

What happened

Why does the diode start to glow?

Under the experimental conditions, a chemical reaction occurs: electrons from magnesium Mg are transferred to copper Cu. This movement of electrons is an electric current. As it passes through the LED, it causes it to glow. Thus, the installation assembled in this experiment acts like a battery - a chemical source of current.

To learn more

The participants in this experiment - copper Cu and magnesium Mg - are very similar. Both of them are metals. This means that they are quite malleable, shiny, and conduct electricity and heat well. All these properties are consequences of the internal structure of metals. It can be thought of as positive ions arranged in a certain order, which are held together using electrons common to the entire piece of metal. It is because of this commonality that electrons can “walk” throughout the entire volume of the metal.

Despite the common motifs in structure, copper and magnesium are different from each other. The overall “pack” of electrons is held in a piece of copper more strongly than in the case of magnesium. Therefore, purely theoretically, we can imagine a process in which electrons from magnesium “escape” to copper. However, this will lead to an increase in charges: positive in magnesium and negative in copper. This cannot continue for long: due to mutual repulsion, it will be unprofitable for negatively charged electrons to move further into copper. The charge is thus collected at the contact surface of two different metals.

Interestingly, the extent to which electrons are transferred from one metal to another depends on temperature. This connection is used in electronic devices that measure temperature. The simplest such device that uses this effect is thermocouple. The use of thermocouples is now widespread, and they form the basis of electronic thermometers.

Let's return to our experience. In order for electrons to constantly transfer from magnesium to copper, and for the process to become irreversible, it is necessary to remove the positive charge from magnesium and the negative charge from copper. This is where lemon comes into play. It is important what kind of environment it creates for the copper and magnesium plates stuck into it. Everyone knows that lemon has a sour taste mainly due to the citric acid it contains. Naturally, there is also water in it. A solution of citric acid is capable of conducting electricity: when it dissociates, positively charged hydrogen ions H + and a negatively charged citric acid residue appear. This environment is ideal for removing the positive charge from magnesium and the negative charge from copper. The first process is quite simple: positively charged magnesium ions Mg 2+ pass from the surface of the magnesium plate into the solution (lemon juice):

Mg 0 – 2e - → Mg 2+ solution

The second process takes place on a copper plate. Since it accumulates a negative charge, it attracts hydrogen ions H + . They are able to take electrons from a copper plate, turning first into H atoms, and then almost immediately into H 2 molecules, which fly away:

2H + + 2e - → H 2

Why can’t we get by with just one copper-magnesium pair?

The closest analogue of the “copper plate – lemon – magnesium plate” system is an ordinary AA battery. It works on the same principle: chemical reactions occurring inside it lead to the generation of a current of electrons, that is, electricity. You've probably noticed that in some devices AA batteries are arranged in a row (that is, the negative pole of one is in contact with the positive pole of the other). More often they do this not directly, but through wires or small metal plates. But the essence remains the same - this is necessary to increase the force that acts on the electrons, and therefore to increase the current.

Likewise, the copper plate in one piece of lemon is connected to the magnesium plate of another. If you connect a diode with only one copper-magnesium pair, it will not start to glow, but using two pairs leads to the desired result.

To learn more

To describe the force that causes charges to move, that is, leads to the generation of electricity, the concept is used voltage. For example, any battery indicates the voltage value that it can create in a device or conductor connected to it.

The voltage created by one magnesium-copper pair is not enough for this experiment, but two pairs are already enough.

Why do we use copper and magnesium? Is it possible to take some other pair of metals?

All metals have different abilities to hold electrons. This allows you to arrange them in the so-called electrochemical series. Metals that are to the left in this row hold electrons worse, and those that are to the right hold electrons better. In our experience, the electric current arises precisely because of the difference between copper and magnesium in their ability to hold electrons. In the electrochemical series, copper is significantly to the right of magnesium.

We can easily take two other metals - it is only necessary that there is a sufficient difference between their desire to retain electrons. For example, in this experiment, silver Ag can be used instead of copper, and zinc Zn can be used instead of magnesium.

However, we chose magnesium and copper. Why?

Firstly, they are very affordable, unlike silver. Secondly, magnesium is a metal that simultaneously combines sufficient activity and stability. Like alkali metals - sodium Na, potassium K and lithium Li - it is easily oxidized, that is, it gives up electrons. On the other hand, the surface of magnesium is covered with a thin film of its oxide MgO, which is not destroyed when heated up to 600 o C. It protects the metal from further oxidation in air, which makes it very convenient to use in practice.

What other fruits and vegetables can be used instead of lemon?

Many fruits and vegetables are suitable for this experiment. It is enough just for them to have juicy pulp. For example, instead of lemon, you can take an apple, banana, tomato or potato. Even a large grape will do!

All these vegetables, fruits and berries contain enough water, as well as substances that dissociate (break up into charged particles - ions) in water. Therefore, electric current can flow through them too!

What is a diode and how does it work?

Diodes are small devices that can pass electric current through themselves and perform some useful work. In this case, we are talking about an LED - when an electric current passes, it glows.

All modern diodes contain a semiconductor at their core - a special material whose electrical conductivity is not very high, but can increase, for example, when heated. What is electrical conductivity? This is the ability of a material to conduct electric current through itself.

Unlike a simple piece of semiconductor, any diode contains two “grades” of it. The very name “diode” (from the Greek “δίς”) means that it contains two elements - they are usually called anode And cathode.

The diode's anode consists of a semiconductor containing so-called "holes" - areas that can be filled with electrons (actually empty shelves specifically for electrons). These “shelves” can move quite freely throughout the anode. The cathode of the diode also consists of a semiconductor, but a different one. It contains electrons, which can also move relatively freely through it.

It turns out that this diode composition allows electrons to easily move through the diode in one direction, but practically does not allow them to move in the opposite direction. When electrons move from the cathode to the anode, at the boundary between them there is a meeting of “free” electrons in the cathode and electron vacancies (shelves) in the anode. Electrons happily occupy these vacancies, and the current moves on.

Let's imagine that the electrons are moving in the opposite direction - they need to get off the cozy shelves into a material where there are no such shelves! Obviously, this is not beneficial for them and the current will not flow in this direction.

Thus, any diode can act as a kind of valve for electricity to flow through it in one direction but not in the other. It is this property of diodes that has made it possible to use them as the basis for computer technology - any computer, smartphone, laptop or tablet contains a processor based on millions of microscopic diodes.

LEDs, of course, have another application - in lighting and display. The very fact of the appearance of light is associated with a special selection of semiconductor materials that make up the diode. In some cases, the same transition of electrons from the cathode to anode vacancies is accompanied by the release of light. In the case of different semiconductors, luminescence of different colors occurs. Important advantages of diodes compared to other electric light sources are their safety and high efficiency - the degree of conversion of electrical energy into light.

Juicy fruits, new potatoes and other food products can serve as food not only for people, but also for electrical appliances. To generate electricity from them, you will need a galvanized nail or screw (that is, almost any nail or screw) and a piece of copper wire. To detect the presence of electricity, we will need a household multimeter, and an LED lamp or even a fan powered by batteries will help us more clearly demonstrate success.

Mash the lemon in your hands to break down the internal membranes, but do not damage the peel. Insert a nail (screw) and copper wire so that the electrodes are located as close to each other as possible, but do not touch. The closer the electrodes are, the less likely it is that they will be separated by a partition inside the fruit. In turn, the better the ion exchange between the electrodes inside the battery, the greater its power.

The essence of the experiment is to place copper and zinc electrodes in an acidic environment, be it lemon or a bath of vinegar. The nail will serve as our negative electrode, or anode. We will assign the copper wire as the positive electrode, or cathode.

In an acidic environment, an oxidation reaction occurs on the surface of the anode, during which free electrons are released. Each zinc atom loses two electrons. Copper is a strong oxidizing agent and can attract electrons released by zinc. If you close an electrical circuit (connect a light bulb or multimeter to an improvised battery), electrons will flow from the anode to the cathode through it, that is, electricity will appear in the circuit.

Potatoes are naturally an excellent casing and electrolyte for a galvanic cell. Potatoes consistently gave us a voltage of more than 0.5 V per cell, while lemon showed a result of around 0.4 V. The champion in voltage is vinegar: 0.8 V per cell. To obtain higher voltage, connect the elements in series. To power more powerful consumers (fan) - in parallel.

On the surface of the cathode, that is, a negatively charged electrode, a reduction reaction occurs: cations (positively charged ions) of hydrogen contained in the acid receive the missing electrons and turn into hydrogen, which comes out in the form of bubbles. A concentration of acid anions (negatively charged ions) occurs near the cathode, and zinc cations occur near the anode. To balance the charges in the electrolyte, it is necessary to ensure ion exchange between the electrodes inside the battery.

Increased soil acidity is a problem for agronomists, but a joy for electrical engineers. The content of hydrogen and aluminum ions in the soil allows you to literally stick two sticks (as usual, zinc and copper) into the pot and generate electricity. Our result is 0.2 V. To improve the result, the soil should be watered.

It is important to understand: electricity is not generated from lemons or potatoes. This is not at all the energy of chemical bonds in organic molecules that is absorbed by our body as a result of food consumption. Electricity arises from chemical reactions involving zinc, copper and acid, and in our battery it is the nail that serves as the consumable material.