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The four stator conductors 
and 
of a rotating machine are carrying 
currents of the same value, the directions of which are shown in the figure (i). The rotor coils 
- ' and 
- ' are formed by connecting the back ends of conductors ' ' and ' ' and ' ' and ' ', respectively, as shown in figure (ii). The e.m.f. induced in coil - ' and coil - 
are denoted by 
and 
, respectively. If the rotor is rotated at uniform angular speed 
in the clockwise direction then which of the following correctly describes the and ?
fig. (i) cross-section view fig. (ii) rotor winding connection diagram
and have finite magnitudes and are in the same phase.
and , have finite magnitudes with leading
and have finite magnitudes with leading
Magnetic field produced by stator is shown below
The poles formed on stator based on direction of magnetic field are also shown.
Number of poles = 4
If θe = 90°, θm = 45°
Geometry Neutral Axis (GNA) lies at 90° electrical to pole axis ie. at 45° mechanical to poles axis. GNA is shown in figure below.
Since the coils a-a’ & b-b’ lie along GNA, emf induced in each of them is 0.