| 1. | Which of the following method of speed control of D.C. machine will offer minimum efficiency ? | |
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Voltage control method
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Field control method
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Armature control method
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All above methods
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Report Question| 2. | ln case the back e.m.f and the speed of a dc motor are doubled, the torque developed by the motor will ? | |
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remain unchanged
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reduce to one-fourth value
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increase four folds
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be doubled
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| 3. | Which of the fol1owing motors one will choose to drive the rotary compressor ? | |
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D.C. shunt motor
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D.C. series motor
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Universal motor
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Synchronous motor
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| 4. | Which of the following motors is usually used in house-hold refrigerators ? | |
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D.C. shunt motor
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D.C. series motor
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Single phase induction motor (split phase start or induction run motor)
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Reluctance motor
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| 5. | Torque developed by a D.C motor depends upon ? | |
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magnetic field
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current flow through the conductors
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number of conductors
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all above factors
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| 6. | Which of the following D.C. motors has the least drop in speed between no-load and nominal load ? | |
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Series motor without commutating poles
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Series motor with commutating poles
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Shunt motor with commutating pole
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Compound motor without commutating poles
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| 7. | Which of the following statement is incorrect ? If a starter is not used with large D.C. motor, it will draw a starting current which ? | |
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will produce very low starting torque
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will produce excessive line voltage drop
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will damage the commutator
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is many times its full-load current
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| 8. | In a D.C. motor, unidirectional torque is produced with the help of ? | |
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end plates
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bushes
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commutator
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both (b) and (c)
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| 9. | Which of the following motor has high starting torque ? | |
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Synchronous motor
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A.C. series motor
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D.C. series motor
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Induction motor
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| 10. | The simplest form of a motor controller ? | |
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relay
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toggle switch
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drum switch
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magnetic switch
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