1) What is the principle operation of DC Motors?
2) What is back e.m.f in a DC motor?
3) Why is shaft torque less than armature torque in a DC motor?
4) Why series motor cannot be started on no-load?
5) In a generator, the main flux is distorted in the direction of rotation due to armature reaction. Why is it distorted in the opposite direction of rotation in a DC motor?
6) What is speed regulation?
7) How can we control the speed of a DC shunt motor?
8) How can we control the speed of a DC series motor?
9) Why is DC motor current so high?
10) What is the chief advantage of a DC series motor?