back emf and eddy currents (1 Viewer)

[DcM]

help..i ve been asked..

whats the diff between back emf and eddy currents
and are they both produced in motors?

 

[Xayma]

back emf slows down the rotation of the motors.

Eddy currents are small ripple like currents that occur in a moving conductor when going through a magnetic field, they transform kinetic energy---> electrical energy ---> heat energy

Eddy currents are very slightly produced in motors in the armature however in transformers they are produced quite readily, thats why you have laminated outsides.

 

[Constip8edSkunk]

back emf is the emf induced by the relative motion of the moving rotor to the magneticfield and flows in the opposite direction(u can test this using the palm rules) of the input current. this can also b understood by the lenzs law.

Eddie current also an 'application' of teh lenz law are currents induced by relative motion between a magnetic field and a non linear conductor. its name comes from teh shape in which the current moves- small circular 'eddies' .... they generally dun occur in motors

 

[smegthehead]

what happens when you pass current through a coil? - you get a motor, however once you move a current carrying conductor through a magnetic field you also get a generator effect. Because you can't get energy for nothing, a back emf is induced to oppose the motion of the coil. In short if there was no such thing as back emf, what you would have is a perpetual motion machine that would spin forever

 

[zubsta]

thats why LAMINATED soft iron cores are used to lower the effect of eddy currents.