Introduction: (Initial Observation)
Electricity that we use at home is produced by electric generators. Do you know how a generator work? or how does a generator create electricity?
An electric current is created when a magnet is spun rapidly inside a coil of wire. As you see in the conceptual diagram in the right, a turbine (usually powered by water or wind) spins a magnet inside a coil.
This action induces an electric current in the coil that can be used to power a light bulb.
In this project you will study to find out what happens that a magnet can create electricity. You may also construct an electric generator that will power a light bulb.
After you construct a working electric generator, you may study on any additional question on factors affecting the function of an electric generator. Following are two sample questions that can be studied:
- How does the speed of a turning rotor affect the production of electricity?
- How does the number of wire loops in stator affect the production of electricity?
Are you ready for this project?
Invention of electricity did not start with electric generators.
First, battery was made. Battery is a device that converts chemical energy to electricity.
For many years scientists used electricity from batteries and made electromagnet and devices that are based on electromagnet such as telegraph, microphone, speaker, buzzer, telephone and electromotor.
Then the idea came up that if you can use electricity to produce a magnet, maybe you could also use magnet to produce electricity. This is what Edison did. He used magnets to produce electricity. The device that he made is called electric generator.
Learning about electricity also should be in the same order.
You can’t make an electric generator before having knowledge and experience of making an electro motor.
With the same token, you cannot make electro motor before making electromagnet. And all these start from making batteries.
Find out about electricity and how it is produced. Read books, magazines or ask professionals who might know in order to learn about the factors that may affect the production of electricity in an electric generator. Keep track of where you got your information from.
Following are samples of information that you may find.
What is electricity and how is it made?
Electricity is moving electrons in a conductor such as a copper wire. But what can force these electrons to move? There are two different ways that electricity can be made.
First method is using a chemical reaction. For example batteries make electricity by a chemical reaction.
Second method is by using magnet. But how can magnet produce electricity?
For making electricity using magnet, check the following links for information:
- How Electricity is made basic
- How Electricity is made (general information)
- Energy sources for making electricity
- How Electricity is made (in an electric factory)
- How Electricity is made (in an electric factory with a nice drawing, good for display)
- How Electricity is made (in a power plan, similar to the above)
- Power Trip
Making electricity using magnet is not a simple experiment, specially if you want to produce enough electricity to light up a bulb. So most likely you are not going to make an electric generator for your project; but drawings in the above sites may be reproduced in a larger size and be used in your display.
For making electricity using a chemical reaction, visit this link:
Here is also some fundamentals:
All atoms of all elements are made of a nucleus and some electrons revolving around the nucleus in certain orbits.
In conductive material, some of these electrons can also move from one atom to the next. The key piece of information that we need to know is that electrons are sensitive to magnets and can be forced to move with a magnet.
This is the foundation of all power generators. Small power generators use an engine, similar to the engine of a car or engine of a lawn mower that spins a magnet close to a coil of wire and that forces the electrons inside the wire to move and that is electricity.
For larger productions, a wind turbine or water turbine is used to spin a large magnet next to multiple coils of wire.
In some generators, coil of wire spins between the poles of a magnet and the result is still the same or better.
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to examine and display the production of electricity where a magnet moves next to a wire. Show that magnet can push or pull electrons. Two specific questions can be studied in relation to this project are:
- How does the speed of turning rotor affect the production of electricity?
- How does the number of wire loops in stator affect the production of electricity?
The last two questions can change this project from a display project to an experimental project. Students at lower grades may just do a display project; however, students in higher grades must select at least one of the suggested questions and perform related experiments.
Identify Variables: (required for higher grades)
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
For question number 1:
- Independent variable is the speed of turning rotor
- Dependent variable is the production of electricity, measured and described by voltage
- Constants are the generator model and specification
For question number 2:
- Independent variable is the number wire loops
- Dependent variable is the production of electricity, measured and described by voltage
- Constants are the speed of turning and all other specifications of of generator such as size and magnet.
Hypothesis: (required for higher grades)
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. Following is a sample hypothesis:
For question 1:
Amount of electricity made using magnet has a direct relation with the speed of magnet or moving magnetic field. Faster the rotor spins, more voltage must be produced. My hypothesis is based on my common sense and observations of a bicycle generator that loses its light when the bicycle slows down.
For Question 2:
Also the number of loops of wire on the stator or coil must have a direct relation with the amount of voltage produced. As the number of loops of wire increase, more electricity must be produced.
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Experiment 1: Does moving a magnet next to a wire or a coil of wire create electricity?
Introduction: In order to find out the optimum conditions for making electricity using a magnet and some wire, perform some initial experiments.
- Bar magnet with marked S and N poles
- Strand of shielded copper wire
- galvanometer capable of detecting and showing small amounts of electricity (millivolts).
- Remove the insulation from the ends of wire
- Move (shake) magnet next to the wire with different speeds, in different directions and distances from the wire and see how many millivolts is displayed in your galvanometer. Record your observations.
- Wrap the wire around an object to make a coil of wire, so more wire will be exposed to moving magnet and repeat the above tests again.
- Record the maximum millivolts that you observed during your tests.
Picture in the right shows a large Galvanometer.
Experiment 2: Making an Electric Generator.
Introduction: As my last experiment, I wanted to make an electric generator that really works and can light up a light bulb. I found a good design at MiniScience.com that is a small box with a magnet spinning inside the box. The coil of wire winds right over the box. This is a list of material that I used and my step by step procedures.
Following are the material that you need in order to construct a wooden electric generator.
- Wood dowel 3/8″ diameter
- Wood Dowel 1″ diameter.
- Rod magnet 3″ long
- Insulated copper wire 23 AWG, 200 feet
- 1.2 Volt Screw Base light Bulb
- Base for the light bulb
- Small sand paper
- Wood Glue
- 1/2 Square foot Balsa wood (1/8″ diameter)
If you are buying a kit, all the wooden parts are included and they are already cut to the size. So you just need to connect them. If you don’t have a kit, prepare the wooden parts as follows:
- Cut two square pieces from the balsa wood (3.5″ x 3.5″).
- Make a 3/8″ hole in the center of each square.
- Cut four 1″ x 3 7/16.
- Cut a 3/4″ piece from the 1″ wood dowel. Make a 3/8″ hole in the center of it. Insert a 6″ long 3/8″ wood dowel in the hole, apply some glue. center it and wait for it to dry.
- Make another hole with the diameter of your rod magnet in the center of the larger wood dowel piece for the magnet to go through.
Wood dowels after completing the step 4
Wood dowels after completing the step 5
- Insert the magnet in the hole of the wood dowel. Center it and use some glue to secure it.
- Use one large square balsa wood and four smaller rectangular balsa woods to make a box.
- Insert your wood dowel into the hole in the center of the box. At this time the magnet is inside the box.
- Place the other large square to complete the box. Apply some glue to the edges and wait for the glue to dry. By now, you have a box and inside the box you have a magnet that can spin when you spin the wood dowel.
- Wrap 300 turns of copper wire around the box and use masking tape to secure it. (If you divide the wire equally, you will have 150 turns of wire in each side of the wood dowel)
- Remove the insulation from the ends of the wire and connect it to the screws of the bulb holder or base.
- Insert the light bulb
- Spin the wood dowel fast to get the light.
Note: The balsa wood may not be very strong and you will need to wind the wire in the direction in which the wood is stronger. Heavy cardboard may be a better choice for this purpose.
Experiment 3: How does the speed of turning rotor affect the production of electricity?
For this experiment you may use the electric generator that you constructed or use a small bicycle generator (picture in the right).
You must spin the rotor with 3 different speeds (slow, medium, fast) while recording the voltage.
You can use any multimeter for this measurement; however, you must make sure that you are setting it to AC voltage. AC stands for Alternative current. In alternative current, electrons swing back and fort inside the wire.
Experiment 4: How does the number of wire loops in stator affect the production of electricity?
For this experiment you must construct 3 different generators. These three generators will be identical on all parts except the number of loops of wire in their coil. Select the number of loops to be 100, 150, 200 and 300.
Use a device such as an electric drill set to a certain speed to spin the rotors. Record the amount of AC voltage that you get from each generator.
Your results table may look like this:
|Loops of wire in coil||Maximum volts|
Need a control?
You may use another identical generator with a fixed number of wire loops as your control. In this way every time that you test your experimental generator with a different number of wire loops, you also test your control generator. You do this to show that any change in the produced voltage is caused by the changes in the number of loops of wire in the coil.
Materials and Equipment:
- Galvanometer or voltmeter capable of showing millivolts. (Can be purchased from electronic stores)
- Magnet wire (This is just a resin coated copper wire, You can use any other shielded copper wire instead.)
- Bar magnet (I selected a bar magnet, because it is easier to keep in hand and move. Mine was about 3 inches long, but there are many other sizes available in hardware stores.
- A small Light bulb with base. (1.2 Volts bulb is the best and you will have more chance to see some light)
Where to buy the materials?
Always compare the prices and qualities to make sure you will get the most for your money. I think you will save time and money if you buy everything from one place. A complete set of materials for experiment 2 is available at MiniScience.com. If you want to purchase locally, magnet wire may be purchased from “Motor/Generator repair shops”; Wood may be purchased from craft stores. Magnet is available at industrial supply shops and some farm suppliers.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
Following are some sample results.
Results/ Notes from Experiment 1:
Trial 1: Initial experiment results were positive. Any movement of magnet next to the wire caused a slight movement in the galvanometer. It seemed very easy, so I decided to make it big and turn on my light bulb as soon as possible.
Trial 2: I wrapped some magnet wire around a pen (about 200 rounds), attached the two ends of wire to the light bulb and started to move the magnet. Surprisingly it produced no light. I thought since now 200 times more wire is exposed to the moving magnet, it should produce 200 times more electricity, and it should be enough to turn on the light. So I checked with galvanometer and that also showed very small electricity.
Trial 3: I thought since the magnet in trial 2 was outside the coil, lots of magnetic force is being wasted. So I got a plastic tube, inserted the bar magnet, securely closed both ends of the tube and wrapped it with 200 rounds of wire and connected the light bulb again. This time magnet is inside the coil and no magnetic force is being lost and I should get enough electricity. I picked up the tube/coil and started to shake it as fast as I could. The magnet was moving from one end of the tube to the other end at least 3 time per second. But still there was no light and galvanometer showed little motion.
Now I was thinking “How did this people invent electricity?”. Instead of continuing experiments I started to find a reason for the failure of the last two trials.
In the second experiment, the diameter of the coil was very small, so the moving magnetic field at the same time affected both sides of the coil, wile the magnet was pushing the electrons of this side of coil to one direction, at the same time it was pushing the electrons of the other side in an opposite direction, so these two forces voided each other and that is why I did not get enough electricity. Solution is a bigger coil and I will test it in trial 4 of my experiment.
In trial 3, since the entire magnet was in the tube, not only the effect of magnet in two sides of coil voided each other, but at the same time the effect of north pole was being voided by the effect of south pole of the same magnet. So that was really wrong.
Trial 4: I made a 2″ diameter coil with 10 loop of magnet wire, attached it to galvanometer and moved the magnet next to the coil. It made 10 millivolts.
Trial 5: I made another 2″ diameter coil with 20 loops of magnet wire, attached it to galvanometer and moved the magnet next to the coil. This time I made 20 millivolts of electricity. This showed that the produced voltage has a direct relation with the number of loops in coil. (Since I was moving the magnet back and forth, I was making an AC current) .
Although making electricity is easy, making enough of that to turn on a light bulb needs some efforts. The experiments showed that in addition to the speed of moving magnetic field, the direction of that in relation to the wire also is an important factor.
It seems that each loop of wire has produced about 1 millivolts in my experiments. So If I want to be able to turn on a 2 volts light bulb just by moving the magnet next to the coil, I need 2000 loops of wire on my coil.
Summery of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
Visit your local library and find books related to electricity. Most such books can be used as references for this project. List the books, magazines and the websites you use in your bibliography.
Make electricity from a lemon
Electricity can also be made by a chemical reaction. This method is used in batteries and creates direct current (DC). Here is a sample recipe of making electricity in chemical way. Material that you need for this experiment are:
citrus fruit (lemons or limes work best)
1 copper screw about 5 cm long
1 zinc screw about 5 cm long
1 holiday light with 5 cm leads (1.3 volts)
Step by step instructions:
1. Roll the fruit under the palm of your hand to soften but be careful you don’t break the skin. Work it gently on a piece of scrap paper or a paper towel.
2. Insert the screws into the fruit about 5 cm apart. Don’t allow the screws to go through the bottom skin of the fruit.
3. Carefully remove about 1 cm of the insulation from the leads on the holiday light. Do not cut into the wire beneath the insulation.
4. Twist one end of the wire around one screw and the other end around the other screw. Presto–you have light!
- Light bulb must be 1.5 volts or less. If you could not find it, buy a cheap flashlight that uses only one AA battery and use it’s bulb for the test.
- If you just use a Voltmeter to show the electricity, you get a better result because small amount of electricity can simply move the handle of a volt-meter, but can not turn on a light bulb.
- If you can not find a copper screw, use a bunch of copper wire or a copper plate or pipe.
- If you can not find a zinc screw, buy a zinc plated screw or a Galvanized Screw.
- More metal surface in contact with fruit results more electricity. Since the produced electricity is so little, you have little chance on turning on a light, but you can definitely show the produced voltage using a multi-meter and you can use that electricity to turn on a digital clock or small digital calculator, because these two need much less electricity than a bulb.
Investigate the probability of using other fruits and vegetables to make electricity. Measure the pH of each “battery” and see if there is a relationship between the pH of the juice and the amount of light that is produced. If you have a multi meter, you can measure the voltage and current produced.
In this sample we are using a copper sulfate solution as an electrolyte(plus a few drops of sulfuric acid). One electrode is copper and the other is zinc. It created 0.9 volts electricity that was not able to turn on a 2.5 volts light bulb. Then I tested with a 1.2 Volts light bulb and got a small light.
Make Electricity from Copper Sulfate Electrolyte
For this experiment we decided to use copper sulfate as electrolyte because copper sulfate is widely available at hardware stores and pull suppliers. You can also get small sheets of copper and zinc from hardware stores. If you could not find zinc, just get a galvanized iron. It does the same thing in a few seconds until the layer of zinc is destroyed. You will need to add a few drops of sulfuric acid for the process to speed up and turn on the light. Sulfuric acid also is known as battery acid and can be purchased from auto parts store. You need diluted sulfuric acid (about 5 to 10%). Acid sulfuric is very corrosive and you must have gloves, goggles and protecting clothing while handling it.
Material needed are:
- 2 plastic or ceramic cup
- 2 sheets of copper (2″ x 4″)
- 2 sheets of zinc (2″ x 4″)
- 50 grams copper sulfate
- 10 cc Sulfuric Acid 10%
- One 1.2 Volts bulb with socket
- Three wires (with alligator clips if possible)
- One Multi-meter (Set to Voltage)
In the first experiment, secure a copper plate and a zinc plate on the sides of the cup as your electrodes. As the picture shows you can bend the sheet toward outside. Use two wires to connect the electrodes to the light bulb holder and screw the bulb. Temporarily remove the zinc plate and then fill up the cup with copper sulfate solution. Now insert the zinc electrode.
Although the process starts and electricity is being produced, the light bulb may still be off. Add a few drops of sulfuric acid to expedite the process and get some light. To stop the process remove the zinc plate. If you want to test the voltage, make sure you unscrew the bulb first.
This process will release hydrogen that is hazardous and breathing that will cause choking. So do the experiment in a well ventilated place and avoid keeping your head right above the cup.
This chemical reaction creates about 0.7 volts that is enough to light up a 1.2 Volts bulb. But is was not able to light up a 2.5 volts bulb that is shown in this picture.
In the next experiment we connected two cups together as shown in the picture. That created about 1.2 volts and produced a small light on our 2.5 volts bulb.
Now you know why I insist on low voltage bulb for this test.
This picture shows the bulb in the last experiment.
Testing other electrolytes such as salt water and lemon juice produced much less electricity and no lights at all.
We decided to repeat the first experiment with 5 small cups and smaller pieces of copper and zinc plated screw instead of zinc.
Multi-meter showed that each cup is producing 0.7 volts and 5 cups together produced 2.3 volts.
Even though we had 2.3 volts of electricity, it could not turn on the light. The reason is that small electrodes can not create enough electric current.