old_blue,
The physics of what goes on inside even a small motor is reasonably impressive. The voltage applied, speed, torque being produced and coil resistance are all involved in determining the exact current through a DC motor at any given set of conditions. The term 'equivalent resistance' is a simplification that I used to try and keep the answer in plain English.
Xl and impedance are much more important in the world of AC motors. Even the mathmaticians had to come up with imaginary numbers to figure out that stuff!
