1. The armature winding of DC machine is placed on the rotor to
(a) reduce losses
(b) escalate commutation
(c) reduce armature reaction
(d) reduce weight [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] B [/accordion-item][/accordion]
2. The yoke of a DC machine is generally made of
(a) carbon
(b) soft iron
(c) cast steel
(d) silicon steel [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
3. Number of magnetic circuits in a four pole DC machine are
(a) one
(b) two
(c) four
(d) eight [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
4. The armature of DC machine is laminated in order to reduce
(a) copper losses
(b) hysteresis losses
(c) eddy current losses
(d) friction frictional losses [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
5. In a DC Machine, the current flow in a armature circuit is
(a) AC
(b) pulsating DC
(c) pure DC
(d) none of the above [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] A [/accordion-item][/accordion]
6. The number of commutator segments in a DC machine is equal to
(a) number of poles
(b) number of conductors
(c) number of coils
(d) number of turns [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
7. As the armature reaction effect increases, the main flux of DC machine is
(a) decreases
(b) increases
(c) remain same
(d) none of the above [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] A [/accordion-item][/accordion]
8. The space wave form of the air gap flux distribution of an DC machine will results change in
(a) current
(b) voltage
(c) torque
(d) none of the above [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] D [/accordion-item][/accordion]
9. In DC machines, slot wedges are generally made of
(a) silicon steel
(b) fibre
(c) impregnated paper
(d) cotton [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] B [/accordion-item][/accordion]
10. The number of brushes used in a lap wound DC machine is always equal to
(a) number of conductors
(b) number of poles
(c) number of coils
(d) number of pole pairs [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] B [/accordion-item][/accordion]
11. In which part of DC machine the eddy current loss is maximum
(a) yoke
(b) field pole
(c) air gap
(d) armature [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] D [/accordion-item][/accordion]
12. In order to reduce the size of DC generator, the magnetic material must have
(a) high permeability
(b) low permeability
(c) high resistance
(d) high reluctance [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] A [/accordion-item][/accordion]
13. In DC machine, the air gap flux distribution in space at no old is
(a) sinusoidal
(b) DC
(c) flat topped
(d) pulsuating [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
14. In DC machine, the teeth in the armature are sometime skewed in order to reduce
(a) copper losses
(b) iron losses
(c) magnetic locking
(d) vibration [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] D [/accordion-item][/accordion]
15. In DC machines if the resistance of carbon brushes increases, the sparking at the brushes
(a) increases
(b) decreases
(c) remains same
(d) none of the above [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] B [/accordion-item][/accordion]