What is the relationship between electrical power and torque in a generator?

[Evil Bunny]

Lets say we have a fixed voltage output on a generator... As we load it down (require more current to flow out of it), the generator needs to apply more torque to supply the power.

Why? What is resisting the rotor from turning?

 

[Curl]

you already said it:

As we load it down (require more current to flow out of it),

there's the answer.



http://en.wikipedia.org/wiki/Lorentz_force

 

[brainyman89]

in this case(the motor is loaded), will the mechanical power converted by the motor be smaller though the intensity of current has increased??

since P(mechanical)=E'*I where E' is the back emf, E' decreases when the motor is loaded?

 

[Evil Bunny]

there's the answer.

That's actually not an answer. It's a reading assignment...

Here's my guess. We induce a current onto a wire with a magnetic field. As current is flowing through that wire, it creates it's own magnetic field that is opposite in polarity to the magnetic field that is being induced onto it... These fields oppose each other which requires more torque from the prime mover to overcome it..?

 

[Evil Bunny]

bump... Is this correct?

Is the induced current creating a magnetic field that is opposite in polarity that makes it resist the current that was originally induced... Which makes them oppose each other, like the prime mover is now trying to overcome the opposing magnetic fields as if you were trying to force two north poles of magnets together?

Is this right?

 

[Curl]

Yes.

Do a search on Lenz's law and it basically says the same thing.