1. The armature of a D.C. generator is usually made of
(A) silicon steel.
(B) copper.
(C) non ferrous material.
(D) cast iron.
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2. The yoke of a dc machine is made of
(A) silicon steel.
(B) aluminium.
(C) cast iron.
(D) stainless steel.
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3. A D.C. generator works on the principle of
(A) Lenz’s law.
(B) self induction.
(C) ohm’s law.
(D) Faraday’s law of electromagnetic induction.
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4. The function of pole shoes in the case of D.C. machine is
(A) to reduce the reluctance of the magnetic path.
(B) to spread out the flux to achieve uniform flux density.
(C) to support the field coil.
(D) all of the above.
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5. In lap winding, the number of brushes are always
(A) double the number of poles.
(B) same as the number of poles.
(C) half the number of poles.
(D) two.
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6. In wave winding, the number of brushes are always
(A) double the number of poles.
(B) same as the number of poles.
(C) half the number of poles.
(D) two.
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7. In wave winding, the number of parallel paths are always
(A) double the number of poles.
(B) same as the number of poles.
(C) half the number of poles.
(D) two.
[accordion clicktoclose=true tag=h4][accordion-item title=”Answer ⇓” state=closed] D [/accordion-item][/accordion]
8. In lap winding, the number of parallel paths are always
(A) double the number of poles.
(B) same as the number of poles.
(C) half the number of poles.
(D) two.
[accordion clicktoclose=true tag=h4][accordion-item title=”Answer ⇓” state=closed] B [/accordion-item][/accordion]
9. Copper brushes in D.C. machine are used where
(A) low voltages and high current involved.
(B) high voltage and small current involved.
(C) both of the above.
(D) none of the above.
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10. Which of the following generator will have negligible terminal voltage while running on no-load ?
(A) Series generator.
(B) Shunt generator.
(C) Compound generator.
(D) Separately excited generator.
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11. The commutator segments are connected to the armature conductors by means of
(A) carbon brushes.
(B) copper lugs.
(C) slip rings.
(D) brazing.
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12. The voltage drop can be expected to be least for
(A) graphite brushes.
(B) carbon brushes.
(C) metal graphite brushes.
(D) none of the above.
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13. The insulation used between the commutator segments is normally
(A) paper.
(B) mica.
(C) graphite.
(D) fabric.
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14. If the field winding resistance of a D.C. generator is increases, then output voltage will
(A) increase.
(B) decrease.
(C) remain unaffected.
(D) fluctuate heavily.
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15. The armature of D.C. generator is laminated to
(A) reduce copper losses.
(B) reduce hysteresis losses.
(C) reduce eddy current losses.
(D) all of the above.
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