- A. Remain unchanged
- B. Reduce to one-fourth value
- C. Increase four folds
- D. Be doubled
D.C. Motors
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In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will
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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
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As the load is increased the speed of D.C. shunt motor will
- A. Reduce slightly
- B. Increase slightly
- C. Increase proportionately
- D. Remains unchanged
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In D.C. shunt motors as load is reduced
- A. The speed will increase abruptly
- B. The speed will increase in proportion to reduction in load
- C. The speed will remain almost/constant
- D. The speed will reduce
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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
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In variable speed motor
- A. A stronger commutating field is needed at low speed than at high speed
- B. A weaker commutating field is needed at low speed than at high speed
- C. Same commutating field is needed at low speed than at high speed
- D. None of the above is correct
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The total losses in a well designed D.C. generator of 10 kW will be nearly
- A. 100 W
- B. 500 W
- C. 1000 W
- D. 1500 W
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These days D.C. motors are widely used in
- A. Pumping sets
- B. Air compressors
- C. Electric traction
- D. Machine shops
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Three point starter can be used for
- A. Series motor only
- B. Shunt motor only
- C. Compound motor only
- D. Both shunt and compound motor
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Which D.C. motor is preferred for elevators?
- A. Shunt motor
- B. Series motor
- C. Differential compound motor
- D. Cumulative compound motor