Classroom experiments and activities
Build a simple generator using easily available material
Grzegorz F. Wojewoda
Very often students have difficulty with understanding the phenomena associated with electro-magnetic induction. At the same time current flowing in home power supply network system is inductive current. In order to help students better understand the physical basis of operation of generators in power plants, I propose building a simple generator model with spinning magnet.
Material needed for the experiment
||The completed generator|
1. Needed backgroundMiddle School
Core curriculum: Electromagnetic induction phenomenon
Lesson Subject: Generation and transmission of electricity
Core curriculum: Electromagnetic induction
Lesson Subject: Generator.
2. Needed materials
The following will be needed to carry out the experiment:
➢ two neodymium magnets,
➢ approx 100m long enamelled copper wire,
➢ light-emitting diode,
➢ empty bottle of milk (or similar),
➢ barbecue stick,
➢ insulating tape,
➢ soldering iron,
➢ two-component Epoxy glue (poxipol)
Fig 1. Material needed for the experiment
|Fig. 2. Piercing the sidewalls of the bottle.|
Then, using a knife, make cuts connecting the top edge of the bottle to the previously made holes.
|Fig. 3. Making cuts along the bottle sidewalls.|
|Fig. 4 Fastening neodymium magnets to barbecue stick|
After the glue has dried, put the rotor in the stator. Put the rotor in the previously prepared holes through the cuts in the bottle sidewalls.
|Fig. 5 Inserting motor into the bottle|
Then, using several turns of an insulating tape, secure the rotor to prevent slipping. The rotor magnets should be placed exactly in the middle of the bottle.
|Fig. 6 Securing the rotor against slipping|
To increase the stability of the generator stator, fasten the bottle side-walls with insulating tape.
|Fig. 7 Reinforcing bottle side-walls with insulating tape|
Next, wind-up the stator windings. During the winding of copper wire, take care not to break the enamel layer. The ends of the windings wires should be near the top edge of the bottle. Make about 200 turns.
|Fig. 8 Winding of generator windings|
After having winded-up the windings, fasten the diode to the bottle.
Through two small holes, cut the diode filaments with a sharp knife blade. Diode filaments should not come in contact with each other.
|Fig. 9 Attaching the LED to the bottle|
Solder diode tips to windings wires .
|Fig. 10 Soldering diodes to windings wire|
Cover the windings and soldering points using insulating tape : the simple generator model is ready for use. The pleasure of explaining why the LED, during generator operation, does not give a continuous but a flashing light should be left to the students.
|Fig. 11 Ready generator model|
And here you can see how it works: