I feel most comfortable and confident to start with energy conversion law to arrive at an equation that sums up the initial torques acting on an armature of electric motor. This is just a review exercise in ece subject but I’ve tried approaching the problem from a very basic physics law I mentioned in a way to verify or to derive the torque equation in its ready form presented and discussed in my resource material that is mainly an engineering text that assumes its engineering students to have already mastered the basic background on how that torque equation came to be.