The Flying Sorcerors

Something has bothered me about the design of Purple's electrical
generator, and its simply that what he describes stands no chance of
working. Instead of permanent magnets, he is describing electrical coils -
for which you would need an electrical current to create the necessary
magnetic field for the other coil to cut through to generate electricity.

Well thats how I read it!!

Stephen

steve.RemoveThis@antispam.sforbesa.cix.co.uk (Stephen Forbes) wrote in message news:<memo.20040816215726.749A.RemoveThis@sforbesa.compulink.co.uk>...
> Something has bothered me about the design of Purple's electrical generator,
> and its simply that what he describes stands no chance of working. Instead of
> permanent magnets, he is describing electrical coils - for which you would
> need an electrical current to create the necessary magnetic field for the
> other coil to cut through to generate electricity.


I don't remember that story; possibly I haven't read it yet. However, I
remember reading about generators that rely upon magnetic fields generated by
the generator itself, to generate the electricity. What happens is that a very
small magnetic field is always present; at the start the generator produces
only a very small amount of electric current as a result. That electric current
powers up the electromagnets, which then produces more magnetic field,
producing even more electric current. The net result is an electric current
that increases exponentially for small currents.

The feedback loop has to become non-linear for large currents, or the
exponential increase would continue until the generator burned out. However,
this is pretty much automatic. You're creating electric current out of nowhere,
and that's OK because current isn't conserved (except in a sense that doesn't
cause problems here). However, you're not creating electric power out of
nothing, energy is conserved. the power coming out has to come from whatever it
is that's keeping the the coils turning. Long before there's any danger of
burning out a (properly designed) generator of this type, the increased work
that has to be done to keep the coils rotating, causes the rotator to slow down,
terminating the exponential growth phase.