Question

which of the following is not used by commercial electric motor
1.an 3lectromagnet to rotate armatur
2.permanent magnet to rotate armature
3.a soft iron core on which the coil is wound
4.non of the above​

Answer 1

Explanation:

about combination of soft iron core and coil is Colin and checked its enhanced the power of motor thus commercial electric motor do not use permanent magnet to rotate the armature because for permanent magnet Harvey and problem strong magnetic field in the region