A 6 pole d.c. generator runs at 1200 rpm on no load and has a generated emf of 250 v. If armature diameter is 350 mm and the radial airgap between field poles and armature is 3mm. The axial length of field poles is 260 mm and the field pole effective coverage is 80% including fringing. If the armature has 96 coils having 3 turns per coil and is waind duplex lap, calculate
i) Flux per pole
ii) Effective pole arc length
iii) Average air gap flux density.