Why Do Generators Use Coils Instead of Pipes?

[Undacuva]

Hi,
I understand you can induce an electrical current by passing a magnet through a copper pipe. If so, why do generators (and motors for that matter) use coils in stead? Do coils allow a stronger current or greater efficiency?
Where can I go to find out the most energy-efficient design for a generator I can build at home?

 

[davenn]

I understand you can induce an electrical current by passing a magnet through a copper pipe. If so, why do generators (and motors for that matter) use coils in stead?

There's a couple of significant reasons
a hint for one of them ... what is the difference between a pipe and a wire ?Dave