Question

please give the answer of b,c and d

Answer 1

b) After every 90 degrees the rotation would stop due to the gap in the split ring, but the momentum of the coil keeps it moving for just a little longer until the coil experiences a force again and the coil moves for another 90 degrees. Then, without a split ring commutator, this same process will occur but in the opposite direction, and then motor will constantly go back and forwards 180 degrees. But a split ring commutator reverses the current, so that the current in the armature is unidirectional
c) The direction of magnetic field is from N-pole to S-pole
e) The electrical energy in the external circuit is converted into machenical engery which rotates the armature coil