In D.C. machines the usual limit of slot pitch is________________?

A. Between 5 to 10 mm
B. Between 10 to 15 mm
C. Between 15 to 20 mm
D. Between 25 to 35 mm

The operation of a D.C. machine with large air gap lengths is comparatively_____________?

A. Quiet
B. Nosiy
C. Either of the above
D. None of the above

In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made____________?

A. Equal to that of armature mmf
B. Less in comparison with the armature mmf
C. Large in comparison with the armature mmf
D. None of the above

In a D.C. machine, the value of peripheral speed should not, normally, exceed___________?

A. 10 m/s
B. 20 m/s
C. 30 m/s
D. 40 m/s

The weight of copper of both armature and field windings decreases with __________ in number of poles?

A. Increase
B. Decrease
C. Either of the above
D. None of the above

In a D.C. machine the current per brush arm should not be more than_____________?

A. 100 a
B. 200 a
E. 300 a
D. 400 a

In D.C. machines the width of the duct is usually_____________?

A. 4 mm
B. 6 mm
C. 8 mm
D. 10 mm

In D.C. machines, the ________ in field mmf results in increase in size and cost of machines?

A. Increase
B. Decrease
C. Either of the above
D. None of the above

Which of the following methods may be adopted to reduce the effects of armature reaction ?

A. increase in length of air gap at pole tips
B. increasing reluctance of pole tips
C. compensating windings
D. interpoles

In D.C. machines the number of slots per pole usually lies___________?

A. Between 2 to 4
B. Between 6 to 8
C. Between 9 to 16
D. Between 20 to 30