A 6-pole wave connected armature has 200 conductors and runs at 1000 rpm. The EMF generated is 500 V. Find the useful flux per pole.

A DC shunt motor is running at its rated speed. If a rheostat connected in the field circuit is adjusted such that the resistance of the field winding circuit increases, what will be the effect on the motor speed, assuming the supply voltage and load torque remain constant?

In large DC machines, how is the demagnetizing and cross-magnetizing effect of armature reaction effectively neutralized?