Generators convert energy from such sources as oil, gas, and wind into electrical energy. Like motors, they use the link between electricity and magnetism. A motor uses electric current to produce a magnetic field that creates motion; but a generator uses the changing magnetic field produced by motion to create an electrical voltage. Generators convert energy with little waste, but much energy is wasted when fuel is burned to work them.


A wind turbine is a modern, scientifically designed version of a windmill. Its gently turning blades, which rotate to face the wind, are connected to a gearbox. The gearbox turns a generator at the much higher speed needed for the efficient generation of electricity.


One kind of generator is called an alternator. It produces alternating current – electric current that continually reverses its direction of flow. The alternator has coils of wire mounted on a spindle that turns inside a magnet (usually an electromagnet). The part that turns is called the rotor. As the rotor turns, its wires cut through the field of the magnet. This generates a voltage that drives current through the bulb.


By the time the rotor has gone through half a turn, the direction in which the wires are moving through the field has reversed. This means that the voltage across the wires is reversed, and so is the current through the light bulb. This is how the alternator produces alternating current. Most generators are alternators, because alternating current can be used with transformers to change the voltage of an electricity supply.


It takes 300 wind turbines to match the power of one generator in a power station. This is why they are usually grouped together in large numbers on wind farms. Wind farms take up a lot of space, so in future they may be built out at sea. As winds are powered by the Sun, they will still be blowing and providing energy when fossil fuels, such as coal and oil, have run out. Using wind power also cuts pollution from burning these fuels, and avoids the dangers of nuclear power.



Copyright © 2007 Dorling Kindersley


Special Books for the Kids You Love
Celebrate 20 years of sharing love to the moon and back with the anniversary edition of Guess How Much I Love You, one of the world’s best-loved picture books. Plus, search our Book Finder for more great book picks. Brought to you by Candlewick Press.

Vote Now for the Children's & Teen Choice Book Awards
Voting is open now through May 3 for the Children's and Teen Choice Book Awards — the only national book awards program where the winning author, illustrator, and books of the year are selected by young readers. Encourage your child to vote for his favorites today!

Top 10 Math & Science Apps for Your Whiz Kid
Looking for the best math and science apps for kids? Check out these cool apps for all ages, which will grow your child's love of the STEM subjects (science, technology, engineering, and math).

Registered for Kindergarten — Now What?
Wondering what to do now that you've signed your child up for kindergarten? Try our award-winning Kindergarten Readiness app! This easy-to-use checklist comes with games and activities to help your child build essential skills for kindergarten. Download the Kindergarten Readiness app today!

stay connected

Sign up for our free email newsletters and receive the latest advice and information on all things parenting.

Enter your email address to sign up or manage your account.

Facebook icon Facebook icon Follow Us on Pinterest

editor’s picks