|Time Required||Very Short (≤ 1 day)|
|Material Availability||This science project requires some specialty electronic components. These specialty items are available in a kit from our partner Home Science Tools.|
|Cost||Average ($40 - $80)|
Neodymium magnets are very strong and can pinch your fingers when they come together. You should keep them away from pets and small children because they can cause serious harm if ingested. As with any magnet, you should keep them away from computers, cell phones, and credit cards.
Adult supervision is required when using a hobby knife.
AbstractYou have probably read all about forms of alternative energy like solar and wind power. But what about human power? With the aid of a coil of wire and some magnets, you can generate electricity with nothing more than a flick of your wrist. In this project, you will build a small hand-powered electrical generator that can power a series of tiny lights. Get ready to save the planet and get some exercise at the same time!
Build a motion-powered electrical generator and experiment to see if there is a relationship between the number of magnets used and the number of LEDs the generator can power.
Ben Finio, PhD, Science Buddies
This science project is based on the "Shake-a-gen" by Dr. Jonathan Hare. Hare, J.P. (2002). Physics on a Shoestring: The Shake-A-Gen. Journal of Physics Education, volume 37, p. 436-439.
- Scotch® is a registered trademark of 3M.
Cite This PageGeneral citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.
Last edit date: 2019-01-16
You are probably familiar with magnets from your everyday life. Magnets come in all shapes and sizes (see Figure 1), but all magnets have one thing in common—they are surrounded by an invisible magnetic field, which has a north pole and a south pole. A magnetic field can push and pull on other magnets. Similar poles (north and north or south and south) repel each other; opposite poles (north and south) attract each other.
Figure 1. (Left) A bar magnet with its north and south poles labeled with N and S, respectively. (Center) A "horseshoe" magnet. The magnet's poles are attracting tiny iron filings. (Right) Two tiny cylindrical magnets next to a matchstick to show their size. Each type of magnet is surrounded by an invisible magnetic field.
Did you know that there is actually a relationship between magnets and electricity? Electrical current flows through all of the electronic devices you use every day, from table lamps and toasters to computers and cell phones. Electrical current is carried by conductors—usually metal wires that allow electricity to flow easily. It turns out that when you move a magnet near a conductor, the magnetic field causes (or induces) a current in the conductor. This is called magnetic induction, and this principle is used in generators to generate electricity. Most generators involve coils of wire (Figure 2), which let you fit a long length of wire into a tiny space. There are many different kinds of generators. Some are very complicated and involve multiple coils and multiple magnets, while some are simple and have just one coil and one magnet. Some are very large (like power plants that power entire cities), while some are very small, and can fit inside portable radios or flashlights (Figure 2). You can read more about electromagnetism in the Science Buddies Electricity, Magnetism, & Electromagnetism Tutorial.
Figure 2. (Top) An illustration of a typical wire coil. Wrapping wire into a coil lets you fit a very long length of wire into a small space. (Bottom) A picture of a flashlight with a wire coil and a magnet inside. Shaking the magnet through the coil generates electricity.
In this electronics science project, you will build a simple generator with a single coil of wire and a magnet, kind of like the flashlight shown above. To test your generator, you will use light-emitting diodes, or LEDs for short. LEDs are the tiny lights you see in many electronic devices. Using more LEDs requires more electricity, so you will investigate whether using more magnets (and thus increasing the strength of the magnetic field in your generator) allows you to light up more LEDs.
Note: The flashlight in Figure 2 contains some additional circuitry that lets it store electricity for later use. The generator you will build in this science project is very simple and does not store energy—the LEDs will only light up while you are shaking it. If you want to build your own shake-to-charge flashlight, see the Make It Your Own Tab.
Terms and Concepts
- Magnetic field
- Electrical current
- Magnetic induction
- Light-emitting diode (LED)
- What is magnetic induction? How can it be used to generate electricity?
- Does stacking multiple magnets together make their magnetic field stronger?
- Do you think a stronger magnetic field will generate more electricity (light up more LEDs)? Or does the strength of the magnetic field not matter?
- How can generators be used to power devices so they never need new batteries? Can you find examples of products that advertise never needing batteries?
- Science Buddies Staff. (n.d.). How to Use a Breadboard. Retrieved July 20, 2016, from http://www.sciencebuddies.org/science-fair-projects/breadboard-tutorial
- Andrew Rader Studios. (n.d.). Magnets. Physics4Kids. Retrieved September 25, 2013, from http://www.physics4kids.com/files/elec_magnets.html.
- Andrew Rader Studios. (n.d.). Current. Physics4Kids. Retrieved September 25, 2013, from http://www.physics4kids.com/files/elec_current.html.
- Andrew Rader Studios. (n.d.). Faraday's Law. Physics4Kids. Retrieved September 25, 2013, from http://www.physics4kids.com/files/elec_faraday.html.
For help creating graphs, try this website:
- National Center for Education Statistics, (n.d.). Create a Graph. Retrieved June 2, 2009, from http://nces.ed.gov/nceskids/createagraph/
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These specialty items can be purchased from our partner Home Science Tools:
- Shaking Up Some Energy Kit (1). Includes:
- 30 AWG magnet wire (1 spool containing 783 feet)
- 12x3 mm neodymium magnets (6)
- Red LEDs (10)
- Note: the project only requires 6 LEDs, but you may want to have a few extra on hand in case you break or lose some.
- Mini solderless breadboard, 1.9 x 1.3 inch (1)
- Alligator clip test leads (1 pack of 2 leads)
- Fine-grit sandpaper
You will also need to gather these tools and supplies:
- Optional (but recommended): Impact-resistant safety glasses, available from Amazon.com
- Card stock, 8.5 inch x 11 inch sheet. Alternatively, a sheet of super heavyweight construction paper or two 5 inch x 8 inch note cards may be used.
- Corrugated cardboard, roughly 3 inches x 6 inches
- Hobby knife. Alternatively, a utility knife may be used, but a hobby knife is preferred.
- Pen or pencil
- Scotch® tape
- Craft glue
- Optional: Power drill, which can speed up the process of winding the wire coil for your generator
- Lab notebook
Recommended Project Supplies
Safety Notes about Neodymium Magnets:
- Handle magnets carefully. Neodymium magnets (used in this science project) are strongly attracted and snap together quickly. Keep fingers and other body parts clear to avoid getting severely pinched.
- Keep magnets away from electronics. The strong magnetic fields of neodymium magnets can erase magnetic media like credit cards, magnetic I.D. cards, and video tapes. It can also damage electronics like TVs, VCRs, computer monitors, and other CRT displays.
- Keep magnets away from young children and pets. These small magnets pose a choking hazard and can cause internal damage if swallowed.
- Avoid use around people with pacemakers. The strong magnetic field of neodymium magnets can disrupt the operation of pacemakers and similar medical devices. Never use neodymium magnets near persons with these devices.
- Use the magnets gently. Neodymium magnets are more brittle than other types of magnets and can crack or chip. Do not try to machine (cut) them. To reduce the chance of chipping, avoid slamming them together. Eye protection should be worn if you are snapping them together at high speeds, as small shards may be launched at high speeds. Do not burn them; burning will create toxic fumes.
- Be patient when separating the magnets. If you need to separate neodymium magnets, they can usually be separated by hand, one at a time, by sliding the end magnet off the stack. If you cannot separate them this way, try using the edge of a table or a countertop. Place the magnets on a tabletop with one of the magnets hanging over the edge. Then, using your body weight, hold the stack of magnets on the table and push down with the palm of your hand on the magnet hanging over the edge. With a little work and practice, you should be able to slide the magnets apart. Just be careful that they do not snap back together, pinching you, once you have separated them.
- Wear eye protection. Neodymium magnets are brittle and may crack or shatter if they slam together, possibly launching magnet fragments at high speeds.
Building Your Generator
First you will need to build the "coil form," the paper tube that you will use to wrap your wire coil. To start, you will make a small tube that acts as a spacer between the magnet and the actual coil form to ensure the coil form is big enough and the magnets do not get stuck.
- Cut a piece of card stock that is roughly 7 centimeters (cm) x 15 cm, as shown in Figure 3.
Using all six magnets stacked together as a guide, roll the card stock tightly into a tube, as shown in Figure 3 (the resulting tube should be 7 cm long).
- Important: Remember to follow all the safety rules listed above for neodymium magnets.
- If your magnets come with small, plastic spacers between them, carefully remove the spacers from the stack before using the magnets as a guide to create the tube.
- Use Scotch tape to secure the tube in place, as shown in Figure 3.
Figure 3. Roll a 7 x 15 cm piece of card stock into a tube, using the magnets as a guide.
Use the tube you made in step 1 as a guide to make a second, larger tube. This is the tube you will actually use as your coil form. The magnets will be able to easily slide back and forth in the larger tube without getting stuck.
- Cut a second piece of card stock that is also 7 x 15 cm.
- Using your first tube as a guide, roll the second piece of card stock into a tube, as shown in Figure 4.
- Use tape to hold the tube in place, and remove the inner tube from the outer tube, as shown in Figure 4.
- When you are done, you can set the smaller tube and stack of magnets aside.
Figure 4. Using the first tube as a guide, roll a second piece of card stock into a slightly larger tube.
Add cardboard circles to the sides of your coil form (the larger tube you just made) to act as guides for wrapping wire around your coil form. All sub-steps are shown in Figure 5.
- Cut two squares of cardboard, roughly 7 x 7 cm.
- Use a pen or pencil to trace one of the circular ends of your coil form onto the middle of one piece of cardboard.
- Sketch a larger circle that reaches the edges of the cardboard square around the smaller circle (this circle does not need to be exact).
Use a hobby knife to cut out the smaller, inner circle.
- Important: Be very careful when using the knife. Young children should have adult supervision. Be careful not to cut into the surface you are working on, like a table top. You may want to use a scrap piece of cardboard or a cutting mat.
- Use the hobby knife or scissors to cut out the larger, outer circle.
- Repeat steps 3.b.–3.e. for the other piece of cardboard.
Press both pieces of cardboard onto the ends of your coil form, placing them about 1.7 cm apart (just far enough for the stack of all six magnets to fit in between them).
- Note: If the cardboard pieces do not easily fit around the coil form, you can carefully use the knife to make the inner circles slightly larger. You do not want to damage the coil form by forcing it in the circle.
- Use glue to secure both cardboard cutouts in place on the coil form. Wait for the glue to dry completely before you continue to step 4.
Figure 5. Cut out cardboard circles and glue them onto your coil form (the larger card stock tube), as shown here. Note: The bottom left image shows the stack of magnets so you know how far apart to space the cardboard pieces — the magnets will not actually stay in this position.
Wind wire around your coil form.
- Unwrap about 60 cm of magnet wire from the spool it came in (do not cut the wire yet!).
- Use tape to secure the wire to the inside of one of the pieces of cardboard, about 30 cm from the end of the wire. This means you should have about 30 cm of wire dangling off of your coil form, as shown in Figure 6.
Carefully and tightly wrap the wire around the coil form, as shown in Figure 7, below. Count the number of coil wraps you make as you go — you need to complete a total of approximately 1,500 coil wraps. Make sure that the 30 cm segment of dangling wire stays free and does not get wrapped up in the coil; you will need to access it later. Also, make sure that you always continue to wrap the wire in the same direction—do not switch directions or your generator will not work.
- Completing 1,500 coil wraps can take a while to do by hand, so be patient. Do your best to keep track of the number of wraps, but you do not need to do exactly 1,500. It might help to put a tick mark down for every 100th wrap on a piece of paper so you do not completely lose track of where you are.
- Tip: If you have a power drill available, you can use it to speed up the process (see the video below Figure 7 to find out how).
- Tip: To keep the dangling wire out of your way as you wind the coil form, you can push the dangling wire into the coil form's inner tube.
- When you have completed approximately 1,500 wraps of wire, leave about 30 cm of wire dangling off the coil. Then use scissors to cut the other end of the wire. Use tape to secure the wire in place so it does not unwind.
Figure 6. Tape the magnet wire to the inside of one of the cardboard pieces so that there is about 30 cm of wire dangling off of your coil form.
Figure 7. Carefully and tightly wrap the wire around the coil form for a total of approximately 1,500 wraps. This figure shows (top left) zero wraps, (top right) 500 wraps, (bottom left) 1,000 wraps, (bottom right) 1,500 wraps.
Finally, use your square of sandpaper to strip the enamel insulation off of roughly 3 cm segments at the end of both wires that are sticking out of your coil.
- If you do not know how to do this, refer to the Science Buddies Wire Stripping Tutorial.
Testing Your Generator
Set up your breadboard and LEDs.
- You will use a solderless breadboard to easily connect multiple LEDs. You can learn how to use a breadboard in the Science Buddies reference How to Use a Breadboard. The LEDs have metal wires sticking out of them called leads (pronounced "leeds"). These leads can be easily inserted into and removed from tiny holes on the breadboard.
Insert six LEDs into the breadboard in a staggered row, as shown in Figure 8. Important: LEDs have two leads, one longer and one shorter. They represent the positive and negative sides of the LED, respectively. In order for multiple LEDs to be connected in a row (also called in series), the negative lead of one LED must be connected to the positive end of the next LED. Make sure that all of your longer (positive) LED leads are positioned on the left, and all of your shorter (negative) LED leads are positioned on the right or your experiment will not work properly.
- It may help to think about the LEDs like a chain of people holding hands. If all the people are facing the same direction, one person's right hand is holding the next person's left hand, and that person's right hand is holding the next person's left hand, and so on.
- See the Technical Note, below, for additional information about LEDs and breadboards (you do not need to understand that information to complete this science project).
Figure 8. Arrange six LEDs in a staggered row on the breadboard, as shown here. (Top) A photograph of the actual breadboard. (Middle) A zoomed-in photo of the LED leads pressed into the breadboard holes. (Bottom) A top-down diagram of the breadboard showing the LED lights (red circles) and the holes to place the LED leads into (the small, solid gray circles). Remember to make sure all the longer LED leads are facing left, and all the shorter LED leads are facing right.
This information is not essential to complete the science project; it is just provided for students who are interested in learning more.
LED stands for light-emitting diode. A diode is like a one-way door for electricity—it only lets electrical current flow through in one direction. "Light-emitting" diode means that LEDs will light up when electrical current flows through them. Since LEDs act like one-way doors, that is why you must make sure all the LEDs are facing in the same direction when you connect them. Otherwise they would prevent electrical current from flowing in either direction, and would never light up. This is easy to see if you draw a circuit diagram for the LEDs. In circuit diagrams, LEDs are represented by triangle symbols that show the direction electricity can flow, like in Figure 9:
Figure 9. The triangle symbol with a line at the tip represents a single LED. When multiple LEDs are all connected facing the same direction, electrical current can flow through them. If just one LED is placed backwards, then electrical current cannot flow at all.
Solderless breadboards provide a convenient way to quickly connect or remove electronic components in a circuit. The small breadboard you are using in this science project has 17 rows of 10 holes each. Each row is split in half into five columns. Each half-row of five holes is electrically connected inside the breadboard. This is what allows you to connect the LEDs together, even though their leads are not touching. Figure 10 highlights each set of connected holes with yellow rectangles:
Figure 10. Each half-row of the breadboard, consisting of five holes, is electrically connected.
This means that it does not actually matter how exactly you put the LEDs into the breadboard, as long as the leads of each adjacent LED are connected to the same row on the breadboard (and the LEDs are all facing the same direction). The three configurations in Figure 11 below all do the same thing electrically:
Figure 11. These three breadboard LED arrangements are all electrically equivalent. In each case, the leads of adjacent LEDs are connected through rows in the breadboard (highlighted by the yellow rectangles).
- Create a data table in your lab notebook, like Table 1, below:
|Number of LEDs||Number of Magnets Needed to Light Up|
Use your alligator clips to connect the first LED to your coil form (which will function as a generator), as shown in Figure 12.
With the breadboard facing you, as shown in Figure 12, clip the red alligator clip onto the left-hand (longer) lead of the first LED. Clip the black alligator clip onto the right-hand (shorter) lead of the first LED or the left-hand (longer) lead of the second LED.
- Remember that the right-hand lead of the first LED and the left-hand lead of the second LED are electrically connected by the breadboard, so you can attach the alligator clip to either one.
- Important: Make sure that the red and black alligator clips do not touch each other. This will create a short circuit and will prevent your LED from lighting up.
- Clip the other end of each alligator clip onto one end of the wire from your coil. Be sure to clip on to the parts of the wire where you sanded off insulation.
- With the breadboard facing you, as shown in Figure 12, clip the red alligator clip onto the left-hand (longer) lead of the first LED. Clip the black alligator clip onto the right-hand (shorter) lead of the first LED or the left-hand (longer) lead of the second LED.
Figure 12. Connect the first LED to your generator coil with alligator clips, as shown here.
Now, you are finally ready to test your generator.
- Take your entire stack of six neodymium magnets and drop them inside the card stock tube of your generator. Important: Remember to follow all the safety rules listed above for neodymium magnets.
- Cover the ends of your generator with your thumb and fingers so the magnets do not fall out, and quickly shake it back and forth (but be careful not to shake loose the wires or breadboard attached to it!). Try to shake your generator at a consistent speed for all of your trials.
- Does the LED light up? You should see the LED flicker as you shake the magnets inside the generator.
- If the LED does not light up at all, look at the Help tab for troubleshooting tips.
The LED flickers because your generator creates alternating current (AC). This means that the electrical current alternates between positive and negative as you shake the generator. Since current can only flow through LEDs in one direction, the LED will only light up half of the time, and appears to flicker. Lighting up the LED continuously would require additional circuitry to make direct current (DC).
Determine how many magnets are required to light one LED.
- Now, take the magnets out of your generator and carefully remove one magnet from the stack of six. Set it aside, away from the other magnets.
- Put the stack of five magnets back inside your generator and shake it again. Does the LED still light up?
- Keep removing magnets until the LED no longer lights up. What is the minimum number of magnets required to light a single LED? Enter your result in the data table in your lab notebook.
Determine how many magnets are required to light two LEDs.
- Move the black alligator clip from the short lead of the first LED (or the long lead of the second LED) to the short lead of the second LED (or the long lead of the third LED), as shown in Figure 13. Leave the red alligator clip in place.
- Start over with all six magnets. Remove one magnet at a time, and test your generator until the LEDs no longer light up. Record the minimum number of magnets required to light two LEDs in your data table.
Figure 13. In order to test two LEDs, leave the red alligator clip in place. Move the black alligator clip to the shorter (right-hand) lead of the second LED.
Repeat step 6 for three, four, five, and six LEDs.
- Each time, move the black alligator clip to the shorter (right-hand) lead of the next LED (or the longer, left-hand lead of the LED after that), as shown in Figure 14.
- Each time, start over with all six magnets, and remove one magnet at a time until the LEDs no longer light up. Record the minimum required number of magnets in your data table.
- Note: If you are having trouble getting the LEDs to light up, try flipping your magnets around. Sometimes when you wind a 1,500-wrap coil by hand, it can become a bit lopsided, and the amount of electricity that is generated will not be perfectly symmetric as you shake it back and forth. As a result, your magnets might work better facing in one direction than in the other. So, if the LEDs do not light up at all, always flip the magnets around and try again before you record results in your data table.
Figure 14. The black alligator clip connected to the third, fourth, fifth, and sixth LEDs (top left, top right, bottom left, and bottom right, respectively).
When you have finished testing all six LEDs, analyze your results.
- Make a graph of the data from your data table, putting the number of LEDs you tried to light up on the x-axis and the number of magnets that were required to light up the LEDs on the y-axis.
- Do you see a relationship between the number of magnets and the number of LEDs that you can light up? What was your hypothesis about this relationship?
- How can you explain your results? Does adding more magnets make a stronger magnetic field? Is there a relationship between the strength of a magnetic field and the amount of electricity induced in the coil?
For troubleshooting tips, please read our FAQ: Human-Powered Energy.
If you like this project, you might enjoy exploring these related careers:
- If you have access to an oscilloscope, try using it to test your generator. What does the resulting waveform look like, and how does it change with different numbers of magnets?
- The simple generator in this science project can only instantaneously light an LED while you are shaking it—it cannot store the energy for use later. Can you build a circuit to store the energy, and even make your own shake-to-light flashlight?
- Build a larger generator—either using more/bigger magnets, more wraps of wire, or both. How do these things affect how much electricity is generated, or how many LEDs you can light?
- Each individual LED requires a certain amount of voltage in order to light up. Whether the voltage required changes when you hook up multiple LEDs depends on whether you connect them in series or in parallel. Research series and parallel circuits, and use the number of LEDs to estimate the maximum voltage from your generator.
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Frequently Asked Questions (FAQ)
Next, try adding more magnets. Just one magnet may not be sufficient to light the LED.
If the LED still does not light up, there might be something wrong with your circuit. Check the following:
- Make sure you used sandpaper to remove insulation from both ends of the copper wire, as described in Step 5 of the Procedure under "Building Your Generator." Try using the sandpaper to remove more insulation, just in case you did not completely remove it the first time.
- Make sure your alligator clips are firmly clipped onto the ends of the copper wire, and that the wire is not loose or sliding around within the clips. The metal surface of the alligator clips needs to be in good contact with the exposed metal surface of the wire in order for electricity to flow.
- Make sure that your LED is pushed firmly into the breadboard. If the LED is loose, it may not be in good contact with the metal inside the breadboard.
- Make sure that one alligator clip is clipped firmly onto each leg of the LED, but make sure the alligator clips are not touching each other. This will create a short circuit and prevent the LED from lighting up.
- Make sure that all the LEDs are facing in the same direction, as described in Step 1.b under "Testing Your Generator." Remember that LEDs act like one-way doors for electricity. In order for electricity to flow through multiple LEDs, they all need to be facing the same direction. You do this by making sure the negative (shorter) lead of each LED is connected to the positive (longer) lead of the next LED.
- Make sure that the leads of adjacent LEDs are placed into the same row on the breadboard. If you place the leads in two different rows, there is no way for electricity to flow between them. It will help if you look at Figure 10 in the procedure, which highlights these connections with yellow rectangles.
Next, try using more magnets. It may require additional magnets to light up more LEDs.
Finally, try flipping your stack of magnets around inside your coil. Ideally, for a perfect coil, the direction the magnets are facing should not matter. However, when you wind a very large wire coil by hand (1,500 turns!), sometimes it can become a bit lopsided, and the amount of electricity generated will not be perfectly symmetric as you shake the magnets back and forth. So, if you still cannot get your LEDs to light up at all (even after adding more magnets), try flipping the magnets around.
Ask an Expert
Contact UsIf you have purchased a kit for this project from Science Buddies, we are pleased to answer any question not addressed by the FAQ above.
In your email, please follow these instructions:
- What is your Science Buddies kit order number?
- Please describe how you need help as thoroughly as possible:
Good Question I'm trying to do Experimental Procedure step #5, "Scrape the insulation from the wire. . ." How do I know when I've scraped enough?
Good Question I'm at Experimental Procedure step #7, "Move the magnet back and forth . . ." and the LED is not lighting up.
Bad Question I don't understand the instructions. Help!
Good Question I am purchasing my materials. Can I substitute a 1N34 diode for the 1N25 diode called for in the material list?
Bad Question Can I use a different part?
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