In case of DC servomotor, the back emf is equivalent to an “electric friction” which tends to:
(a) Slowly decrease the stability of the system
(b) Improve stability of the system
(c) Very rapidly decrease the stability of the system
(d) Have no effect of stability
The question was posed to me in a national level competition.
The question is from Differential Equations of Physical Systems and Dynamics of Robotic Mechanisms topic in chapter Mathematical Models of Physical Systems of Control Systems