NEW ZEALAND PHYSICS TEACHERS' RESOURCE BANK

Bicycle Generator

Poster frame from video: In most browsers, Click on image to play OR Right-click on image and "save target as" to your computer, then play in QuickTime, Windows Media Player, or another player.

The Bicycle Generator with belt guards removed

Abstract
A bicycle is used to spin a generator and power light bulbs.
Portable Yes
Principles Illustrated

Almost all commercial electricity production is based on spinning magnets in coils.

Making electricity is hard work and the scale of electrical energy use in industrialised countries like New Zealand is huge.

When you draw more current from a spinning generator the generator becomes harder to spin.
NCEA & Science Curriculum
PHYS 1.2, PHYS 2.7, PHYS 2.6
Teacher Guide
Would you like to contribute lesson suggestions? Contact us.
Video

mp4 (7 MB) that plays in Windows Media Player, Apple QuickTime, and Real Player: Bicycle Generator.mp4
Instructions

Bicycle generators can be purchased but are not cheap. Hand cranked generators are a more reasonably priced alternative but are not as impressive to students. If you are in the Wellington area we can bring our bicycle generator to your school. If you want to make one yourself, contact us for help as there are a number of technical issues and some safety issues.

There is an interesting aspect of generator design that is deliberately not mentioned in the videos but would be a very good extension topic for keen students in Level 3 physics. In larger scale generators, even most automotive alternators, the spinning magnets are actually not permanent magnets but electromagnets! Part of the electric energy induced in the coils is used to energise the electromagnets. The wires seen extending from the bicycle generator in some of the photos are connected to a battery to energise the electromagnets initially, as is required for such generators. The battery is then disconnected during operation.

Close up of generator assembly

Close up with belt guards in place.

 
Safety

 

Significant voltages can be generated depending on the type of generator used, belt guards should be attached.
Individual teachers are responsible for safety in their own classes. Even familiar demonstrations should be practised and safety-checked by individual teachers before they are used in a classroom.
Related Resources
References

NOTE: We do not take any responsibility for the content of external web sites. We often link to Wikipedia, for example, because we have found a lot of very useful material there. But remember that anyone can post anything on the web anytime, and web sites change over time as well. So check the information before you use it! If you find sources of information that are useful please let us know.

Here's a good animation:
http://www.sciencejoywagon.com/ physicszone/lesson/otherpub/wfendt/generatorengl.htm

New Zealand electricity generation, use, and efficiency:
http://www.med.govt.nz/upload/32800/2006.pdf, http://www.electricitycommission.govt.nz/news/expandlights, many similar publications from the New Zealand Government and other sources. NIWA, The Ministry of Economic Development and the Electricity Commission are good places to start looking for more information. Various sources will give somewhat differing estimates for electricity generation and use but they do not vary by large amounts.

This demonstration is related to PIRA 5K40.80.

Credits

This teaching resource was developed by the Te Reo Māori Physics Project with support from

 

Copyright

Copyright and fair use statement