An armature-controlled DC motor drives an external load with inertia J through a gear transmission system with gear ratio n. The system is shown in the following figure. The armature winding has inductance L and resintance R. The field of the motor is supplied with constant voltage (thus similar permanent magnet DC motor). The inertia of the armature is Jm. The torque generated by the motor is T. The back-emf constant is Kb. Find the transfer function O(s)/Ei(s). ww JL