Make an Electric Generator


An electric generator converts mechanical energy into electrical energy by generating voltage (or electro motive force, e.m.f. for short) that forces electrons to flow in an electric circuit.  This is called electromagnetic induction.  These flowing electrons can be used to make a motor spin or a bulb illuminate.

Things You Need

Magnet wire
Ceramic magnets
Small light bulb
Iron nail
Wire stripper
Pair of scissors
Pencil or pen
Corrugated cardboard
(Touch or hover over each item for more information or alternatives)

How To Make It

Generator 01 Generator 02 Generator 03 Generator 04 Generator 05 Generator 06 Generator 07

Things To Try

By spinning the nail and the magnets, you create a changing magnetic field that generates electricity inside the coil.  This electricity illuminates the light bulb.

How does the brightness of the bulb change when you spin the nail faster? Slower?

What happens when you add another magnet to each side of the nail?

How It Works

When a conducting wire is placed inside of a changing magnetic field, an electric voltage (electro motive force) is induced in the wire.  This phenomenon known as electromagnetic induction, is demonstrated in the animation below.

When the magnet moves into and out of a wire coil, the magnetic field around the coil changes.  The voltmeter's fluctuating needle indicates that a voltage is being induced within the coil.  A faster-moving magnet induces a greater amount of voltage.  When the magnet stops moving, the voltmeter's needle instantly returns to zero (the middle position), showing that a changing magnetic field is required to generate electricity.

The electric generator we just built uses the same principle.  However, instead of moving a magnet in and out to produce a changing magnetic field, a magnet is rotated inside a wire coil.  Once again, the faster the magnet rotates, the faster the change in the magnetic field. This produces greater voltage, making the bulb glow brighter.

Bigshot Connections



[1] "Electrical generator." Wikipedia, The Free Encyclopedia. [Online]. Available: http://en.wikipedia.org/wiki/Electrical_generator. [Accessed: Jan 20, 2010].
[2] "Electromagnetism." Wikipedia, The Free Encyclopedia. [Online]. Available: http://en.wikipedia.org/wiki/Electromagnetism. [Accessed: Jan 20, 2013].
[3] William Beaty, "Ultra-simple electric generator." [Online]. Available: http://amasci.com/amateur/coilgen.html. [Accessed: Jan 20, 2013].