Practice Test: Question Set - 06
1. The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is
- (A) 4.0
- (B) 2.0
- (C) 1.0
- (D) 0.5
2. Which of the following motor has the poorest speed regulation?
- (A) Shunt motor
- (B) Series motor
- (C) Differential compound motor
- (D) Cumulative compound motor
3. The speed of a D.C. motor can be varied by varying
- (A) Field current
- (B) Applied voltage
- (C) Resistance in series with armature
- (D) Any of the above
4. Which of the following motors is usually used in household refrigerators?
- (A) D.C. shunt motor
- (B) D.C. series motor
- (C) Single phase induction motor (split phase
start or induction run motor)
- (D) Reluctance motor
5. Which of the following loss in a D.C. generator varies significantly with the load current?
- (A) Field copper loss
- (B) Windage loss
- (C) Armature copper loss
- (D) None of the above
6. Hopkinson's test on D.C. machines is conducted at
- (A) No load
- (B) Part load
- (C) Full load
- (D) Overload
7. The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by
- (A) Reducing the field current
- (B) Decreasing the armature current
- (C) Increasing the armature current
- (D) Increasing the excitation current
8. The speed of a D.C. shunt motor more than its full-load speed can be obtained by
- (A) Decreasing the field current
- (B) Increasing the field current
- (C) Decreasing the armature current
- (D) Increasing the armature current
9. In D.C. motor which of the following can sustain the maximum temperature rise?
- (A) Slip rings
- (B) Commutator
- (C) Field winding
- (D) Armature winding
10. D.C. series motors are used
- (A) Where load is constant
- (B) Where load changes frequently
- (C) Where constant operating speed is needed
- (D) In none of the above situations
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