TIP: After each
project, look at what you have made and try to trace the path of
electricity through the circuit and understand what is happening. Where
is the electromagnet and what does it do?
the end of the unit, try to apply what you have learned by building an
electromagnet to do some useful task like run a fan or power a toy.
For background about electromagnets (a little abstract for some students but not at all difficult for teachers) visit How an Electromagnet Works. Warning,
the animation on this page is wrong, when a circuit has electricity
moving through it, it makes a magnetic field around it at right angles
to the flow. That means when the switch closes, the compass needle will
point away from the wire. Try it and see for yourself.
The page on How Electric Motors Work is very useful. It shows how a motor changes electrical energy to mechanical energy.
Visit Walk Through a Hydroelectric Project
to see an example of how generators work just the opposite of electric
motors. By using mechanical energy to move magnets past a coil of wire,
you can make electrical energy.
For information on the electromagnetic spectrum, see How the Radio Spectrum Works.
For another interesting motor project, visit Beakman's Electric Motor.
Why are the concepts of this unit important? According to the Consortium for Energy Efficiency
(CEE), electric motors account for 50% of all energy use in the United
States and for two thirds of all industrial energy use. Ask students how
many electric motors they have used in a day and they probably wouldn't
know. The average computer alone contains at least 4 electric motors
(CD drawer open, CD drawer close, CD drive, hard drive). Go to our Inside an Electric Drill page (see left navigation) to see another example of an electrical motor in a common household object.