A DC series motor is driving a constant torque load, at 500 r.p.m., the field turns are divided into two groups connected in series. If the field turns are connected in parallel, then speed will be

In a DC series motor, connecting field windings in parallel reduces the effective number of field turns, thereby reducing the field flux. Since motor speed is inversely proportional to field flux (especially at higher speeds where armature resistance drop is negligible), a reduction in flux leads to an increase in speed. For a constant torque load, the armature current is maintained, and if the flux is halved, the speed approximately doubles.