iron

silicon steel

high carbon steel

stainless steel

two

four

equal to the no. of poles

one

steady d.c.

steady a.c.

pulsating a.c.

pulsating d.c

no effect takes place

current flow is stopped

The direction of current flow is reversed

the magnitude of current flow is decreased

rotating magnetic field past stationary coils

relative motion between the field and the armature coils

converting electrical energy into mechanical energy

rotating the coils around a magnetic field