Calculating Back EMF, Power and Torque for a DC Series Motor 

Glad it helped!

Thanks Warren - glad it was helpful

Hi Elly, the mechanical (rotational) power developed by the armature is dependant on the voltage (back EMF) produced at the armature. There will be power dissipated across the resistance of the armature as you say, but these will be losses (heat) rather than "useful" power.