# Determine resistance of a generator

Ry122
What formula can I use to determine the resistance of an electrical generator?

Ry122
by resistance i mean the force from the magnets that is slowing down the rotation of the coils.

Ry122
since no one has replied i guess its safe to assume its not possible to calculate.

Staff Emeritus
Gold Member
It is most definitely possible to calculate the force, it is a simple application of the the Lorentz force.

Perhaps no one replied because you don't seem to have put any effort into trying to figure it out yourself.

Ry122
http://users.on.net/~rohanlal/58c2b8b14b73d2bafeaaafb80b4a5491.jpg [Broken]
This is the Lorentz formula. It requires me to know the electric field,the particle velocity, magnetic field and the electic charge. I know none of these values.
All I know is how many rpm are required for a certain voltage to be generated.
Is it possible to calculate the force generated with just this information?

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Staff Emeritus
Gold Member
You would also know, or could work out the current, which is the rate of flow of charge.

Ry122
With that would I be able to determine the other required values?

Staff Emeritus