Motors - EMF/Induced currents (1 Viewer)

[laney]

Could someone in a sentence or so, just explain WHEN does induced emf occur, when does induced currents occur, and when eddy currents occur, and if they occur in Motors or Generators, or both?


i'm just so confused with these.


thanks heaps if you can help me

 

[spice girl]

According to Lenz's Law or Faraday's Law of Electromagnetic induction, there will always be an induced emf when a conductor is exposed to a changing magnetic field, and when there is a circuit or path for charge to flow (e.g. laminations restrict paths), there will be an induced current; eddy currents are basically currents induced by fluctuating magnetic fields and its power not harnessed by an external circuit - instead it produces heat and resists relative motion to the magnetic field (sometimes this is unwanted, sometimes intended).

 

[superhubert]

obviously induced currents cant really flow in a motor because there is already a current flowing. but it has its own version, back emf, this opposes the supply emf. induced currents occur whenever there is a conductor present in a changing magnetic field. Thus by lenzes law, it will flow in the opposite direction of the thing that caused it, right?
eddy currents are produced in transformers (and things where physical principals are the same)it also follows lenzes law and opposes motion, ie use in magnetic braking etc. they also produce heat and energy loss (problem in transformers...

 

[laney]

sooooo.......do induced EMF and induced currents OFTEN happen at the same time?

and these occur in generators? right??


just trying to make sure i've got this under wraps

 

[Viator]

Induced EMF / Current occurs in any conductor in a changing magnetic field, but it is specifically harnessed in generators to generate electricity.
It occurs in a motor aswell, but rather in hinders the motor. The induced EMF is called Back EMF, as it oposes it.

 

[Ronnie]

there will always be an induced emf when a conductor is exposed to a changing magnetic field, and when there is a circuit or path for charge to flow, there will be an induced current -- SPICE GIRL

in other words.... emf is will always occur if a conductor is exposed to a changing magnetic field, if the conductor is connected to an outside circuit this emf has somewhere to flow hence it becomes a current

 

[1234567]

now i am confused.
damn i always lose direction

say if in a motor, the current goes left to right in the conductor in the magnetic filed, the back emf would go right to left.
and say we have a generator, that has exactly the same magnetic filed, would the generated electricity be in the direction of the back emf of th emotor, or the conventional current flow in the motor?