This lesson attempts to demystify electromagnetism by having students build their own shake-dynamos with copper coil and magnets. The lesson explains how a moving magnetic field can induce a current in the copper wire, which can then be used to light an LED (or perhaps power some other device). It can serve as a compliment to the battery lesson (electricity through mechanical rather than chemical means), and a prelude to learning about motors.

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Very basic electromagnetism, principles of diodes, current and voltage, AC vs DV

none

solving a simple problem

teamwork

students build little dynamos to directly light LEDs

PEN lessons that meet the requirement are noted in brackets.

none

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Anything with electromagnetism: alternator, bike charger, etc

Perhaps the teacher takes apart a DC motor and passes it around for students to see. The teacher could also push magnets across the table to demonstrate electromagnetic fields.

None

Students will make their own dynamos out of wire, magnets, and some non-magnetic material, for example by rolling paper into a stiff cylinder slightly larger than the magnets and coiling wire around it.

non-magnetic material like cardboard/paper, copper wire, strong magnets, LEDs, razor blade to strip the wire

small DC motor to take apart

Whiteboard to draw field lines, possibly pictures or computer simulations of electromagnetic fields

Ideal class size 20-30 students, with groups of 3-4 to build the dynamos. 1-2 teachers to walk around and ensure that students are on the right track.

Why should students want to participate in this lesson?

learn how electromagnetism works, light up LEDs with science!

Why should teachers want to teach it?

simple demonstration of energy conversion, good intro to electricity generation and background for harder projects

If this lesson (and its prerequisites) were the only PEN lessons someone took, what should they be able to do?

Build a shake dynamo. Explain rudimentary basics of motors, electromagnetic fields, and AC voltage.

If you had to teach this lesson tomorrow morning, what would you spend tonight working on? (assuming that materials were not an issue)

How to explain electricity generation, how to help students figure out the shake dynamo.

If you hadn’t taught this lesson before, what questions would you have for someone who had taught a very similar lesson?

How much information should you explain before it become overwhelming? What metaphors would you recommend using?

If the only materials available were broken radios, TVs, and computers, could you do all the electronics in this lesson? (assuming you had solder, soldering irons, etc.) If not, what would be missing?

You would need a lot of copper wire, and surface-mount LEDs would be hard to use.

If the only structural materials available were dish-cloths, cardboard, and plastic bags, could you make the mechanical bits of this lesson? (assume equipment as above) If not, what would be missing?

Yes.