Shake Dynamo teacher's guide

Background Information


For one dynamo…

  • Enough cardboard/paper/tree bark/etc to roll into a stiff tube (about 4” x 2”)
  • Thin copper wire to wrap about 200-300 coils around tube
  • [NOTE: count the coils! And make sure these dimensions make sense!]
  • several strong magnets that can stack and fit inside the tube with poles on top and bottom
    • (4-5 neodynium disc magnets works well)
    • [figure out how to do this with recycled hard drive magnets]
  • two low-brightness LEDs (ideally red)
  • something to strip the wire: sandpaper or a knife-edge/razor blade
  • something to cover one end of the tube (like tape)


How to make a dynamo:

  1. Make a roll of paper that can loosely fit the magnets inside: about 4” long and 1/2” in diameter
  2. Coil the copper wire around the middle of the tube between 200-500 times, and spread out the coils over about an inch. The more coils, the stronger the current will be— unless it’s too strong and kills the LED. Be careful to keep track of both ends of the coil, and not to squeeze the tube any smaller.
  3. Scrape the coating off for an inch on both ends of the wire. Copper wire is coated with a non-conductive material, which means that electricity can only travel inside the wire.
  4. Attach one LED to both ends of the coil (with one leg of the LED at each end) by wrapping the wires around the leads.
  5. Attach a cover to one end of the tube.
  6. Stack your magnets, and put them inside the tube.
  7. Hold the other end of the tube, and shake the magnets up and down. When you create a strong enough current, the LED should flash on and off.

General Tips:

  • Make and test a dynamo beforehand so you know how they work.
  • If the LED won’t light:
    • Are you shaking it properly? Try giving the dynamo one really hard shake and see if that works.
    • Does the LED work? Test it with a battery to make sure.
    • Make sure that the wire has been stripped well enough and there’s a good connection.
    • Twist the surface end of the coil together with another piece of copper wire, and add more coils to increase the electron flow.

Demo: Invisible Fields

Electromagnetism is difficult to think about in the abstract, so it helps to demonstrate how invisible fields work.

[Note: there may be more interesting experiments out there, which we could use instead!]

Materials: - 2-3 magnets - a piece of cardboard - a compass (optional)

Place one magnet on top of the table. Move the second magnet around under the table, and watch how the top magnet moves. How strong is this invisible magnetic force? How far away must the bottom magnet be before the top magnet stops moving?

Put your compass down on the table, and watch what happens to the needle when you move the magnet around the compass. A compass has a magnetic needle to measure the overall magnetic field of the earth, but your magnet creates a stronger field because it is much closer. Don’t keep the compass close to the magnet for a long time, because this will ruin the compass needle!

Demo: Magnets on the Outside (ie how motors work)

Materials: - an old (preferably broken) motor - tools to take motor apart

Carefully remove the cover of the motor, on the side where the axel sticks out. A flathead screwdriver, or something skinny and strong, will help you take it off without damaging the motor. While your paper dynamo uses magnets inside a wire coil to make an electric field, the motor uses some coils inside a ring of magnets. A motor works the same way, by using a magnetic field to move the electrons inside the wire, but it is designed to maximize the electricity produced.

A motor spins when you send an electrical current through the wire. The opposite is also true: you can create an electrical current by spinning the motor. [NOTE: lead-in to turbine lesson?]

Background Information

Intro to electrons, free in metals

Intro to electromagnetic fields

- pictures of field lines with arrows

AC voltage (compare to battery lesson)

- note how LED only lights up one way - can add another LED in opposite orientation

How-to-teach concepts

- electrons cascade like bumper cars

Local Research:

- where to find copper wire - where to find small magnets, and whether they work

You could leave a comment if you were logged in.