Practice Test: Question Set - 03
1. If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will
- (A) Increase
- (B) Decrease
- (C) Remain same
- (D) Become zero
2. Torque developed by a D.C. motor depends upon
- (A) Magnetic field
- (B) Active length of the conductor
- (C) Current flow through the conductors
- (D) All above factors
3. D.C. generators are installed near the load centers to reduce
- (A) Iron losses
- (B) Line losses
- (C) Sparking
- (D) Corona losses
4. Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversing and speed control
- (A) Drum type controller is used
- (B) Three point starter is used
- (C) Four point starter is used
- (D) All above can be used
5. If the supply voltage for a D.C. motor is increased, which of the following will decrease?
- (A) Starting torque
- (B) Operating speed
- (C) Full-load current
- (D) All of the above
6. No-load speed of which of the following motor will be highest?
- (A) Shunt motor
- (B) Series motor
- (C) Cumulative compound motor
- (D) Differentiate compound motor
7. For starting a D.C. motor a starter is required because
- (A) It limits the speed of the motor
- (B) It limits the starting current to a safe value
- (C) It starts the motor
- (D) None of the above
8. In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be
- (A) Almost negligible
- (B) Rated full-load current
- (C) Less than full-load current
- (D) More than full-load current
9. The starting resistance of a D.C. motor is generally
- (A) Low
- (B) Around 500 Q
- (C) 1000 Q
- (D) Infinitely large
10. The condition for maximum power in case of D.C. motor is
- (A) Back e.m.f. = 2 × supply voltage
- (B) Back e.m.f. = I × supply voltage
- (C) Supply voltage =I × back e.m.f.
- (D) Supply voltage = back e.m.f.
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