electrical engineering Mcqs
1. economics of power generation2. analog electronics3. solid state switching circuits4. parallel circuits5. switchgear and protection6. op amp circuits7. transistor audio power amplifiers8. electrostatics9. heating and welding10. multi stage transistor amplifiers11. passive filters12. network theorems13. regulated d c power supply14. a c fundamentals circuits and circuit theory15. electromagnetic induction16. power electronics17. magnetism and electromagnetism18. transformers19. modulation and demodulation20. d c generators21. semiconductor theory22. single phase induction motors23. semiconductor diode24. hybrid parameters25. digital electronics26. oscillators27. earthing or grounding28. single stage transistor amplifiers29. d c motors30. transistor biasing31. amplifiers with negative feedback32. basic electrical33. electronic instruments34. synchronous motors35. field effect transistors fet36. magnetic circuit37. control systems38. industrial drives39. power generation40. series parallel circuits41. transistor tuned amplifiers42. electrical engineering materials43. rectifiers and converters44. integrated circuits45. scr silicon controlled rectifiers46. cables47. polyphase induction motors48. measurement and instrumentation49. transistors50. electrical machine design51. electrolysis and storage of batteries52. electric traction53. transmission and distribution
5651. In a D.C. generator all of the following could be the effects of iron losses except___________?
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A. Loss of efficiency

B. Rise in temperature of ventilating air

C. Increase in terminal voltage

D. Excessive heating of core

5652. The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by______________?
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A. increasing the excitation current

B. none of the above methods

C. reducing the field current

D. decreasing the armature current

E. increasing the armature current

5653. For constant torque drive which speed control method is preferred ?
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A. Field control

B. Shunt armature control

C. Mechanical loading system

D. Armature voltage control
5654. For the same H.P. rating and full load speed, following motor has poor starting torque_____________?
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A. differentially compounded

B. series

C. shunt

D. cumulativelycompounded

5655. Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?
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A. Shunt motor

B. Series motor

C. Cumulatively compounded motor

D. Differentially compounded motor

5656. Ward Leonard method of speed control is basically a______________?
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A. frequency control method

B. armature controlled method

C. field control method

D. field diverter

5657. The power mentioned on the name plate of an electric motor indicates____________?
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A. the gross power

B. the power drawn in kW

C. the power drawn in kVA

D. the output power available at the shaft
5658. These days D.C. motors are widely used in____________?
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A. electric traction

B. machine shops

C. pumping sets

D. air compressors

5659. In a D.C. shunt motor, speed is______________?
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A. independent of armature current

B. directly proportional to the armature current

C. inversely proportional to the armature current

D. proportional to the square of the current

5660. If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will_________?
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A. become zero

B. remain same

C. decrease

D. increase
5661. In case of conductively compensated D.C. series motors, the compensating winding is provided______________?
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A. as separately wound unit

B. in parallel with armature winding

C. in parallel with field winding

D. in series with armature winding
5662. In D.C. machines fractional pitch winding is used__________?
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A. to reduce the sparking

B. to increase the generated e.m.f.

C. to reduce copper losses

D. to improve cooling

5663. The condition for maximum power in case of D.C. motor is______________?
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A. supply voltage = back e.m.f

B. back e.m.f. = 2 x supply voltage

C. back e.m.f. = | x supply voltage

D. supply voltage = | x back e.m.f

5664. Which of the following motor has the poorest speed regulation ?
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A. Shunt motor

B. Differential compound motor

C. Cumulative compound motor

D. Series motor
5665. During rheostat braking of D.C. series motors_____________?
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A. motor is run at reduced speed

B. motor is reversed in direction

C. motor is run as a generator
5666. If the supply voltage for a D.C. motor is increased, which of the following will decrease ?
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A. Starting torque

B. Full-load current

C. Operating speed

D. All of the above

5667. D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the________________?
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A. shunt motor

B. compound motor

C. any of the above

D. series motor
5668. Which of the following losses are significantly reduced by laminating the core of a D.C. generator ?
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A. Eddy current losses

B. Copper losses

C. Windage losses

D. Hysteresis losses

5669. Which of the following loss in a D.C. generator varies significantly with the load current ?
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A. Windage loss

B. None of the above

C. Armature copper loss

D. Field copper loss

5670. Which of the following method is used for the speed control of DC shunt motor?
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A. all of the above

B. rheostat control method

C. flux control method

D. voltage control method

5671. The losses occurring in a D.C. generator are given below. Which loss is likely to have highest proportion at rated load of the generator ?
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A. armature copper loss

B. field copper loss

C. hysteresis loss

D. eddy current loss

5672. In a differentially compounded D.C. motor, if shunt field suddenly opens____________?
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A. the motor will work as series motor and run at slow speed in the same direction

B. the motor will not work and come to stop

C. the motor will work as series motor and run at high speed in the same direction

D. the motor will first stop and then run in opposite direction as series motor
5673. In which of the following device the generated emf and armature current are in the opposite directions?
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A. dc generator

B. all of the above

C. dc motor

D. transformer

5674. If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking?
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A. any of the above

B. plugging

C. dynamic braking

D. none of the above

E. regenerative

5675. Following motor is used where high starting torque and wide speed range control is required?
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A. None of the above

B. Induction motor

C. Synchronous motor

D. Single phase capacitor start

E. D.C. motor
5676. Why are the D.C. motors preferred for traction applications ?
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A. The speed is inversely proportional to the torque and the torque is proportional to square of armature current

B. Torque is proportional to armature current

C. Torque and speed are inversely proportional to armature current

D. Torque is proportional to square root of armature current

5677. The armature voltage control of D.C. motor provides_____________?
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A. constant torque drive

B. constant voltage drive

C. none of the above

D. constant current drive

5678. What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
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A. The armature may burn

B. The motor will stop

C. The motor will run noisy

D. The motor will continue to run

5679. D.C. generators are installed near the load centres to reduce_____________?
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A. sparking

B. corona losses

C. line losses

D. iron losses

5680. The speed of a D.C. shunt motor can be increased by_______________?
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A. reducing the resistance in the armature circuit

B. reducing the resistance in the field circuit

C. increasing the resistance in field circuit

D. increasing the resistance in armature circuit

5681. D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this______________?
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A. any of the above

B. compound motor

C. shunt motor

D. series motor

5682. By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?
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A. Frame

B. Commutator

C. Stator

D. Shaft

5683. The condition for maximum efficiency for a D.C. generator is______________?
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A. copper losses = 0

B. variable losses = constant losses

C. hysteresis losses = eddy current losses

D. eddy current losses = stray losses

5684. D.C. shunt motors are used for driving____________?
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A. machine tools

B. hoists

C. trains

D. cranes

5685. The hysteresis loss in a D.C. machine least depends on____________?
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A. Volume and grade of iron

B. Rate of flow of ventilating air

C. Maximum value of flux density

D. Frequency of magnetic reversals

5686. Which of the following method of speed control of D.C. machine will offer minimum efficiency ?
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A. Voltage control method

B. Armature control method

C. Field control method

D. All above methods

5687. Which of the following motors is most suitable for signalling devices and many kinds of timers ?
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A. D.C. shunt motor

B. Induction motor

C. Reluctance motor

D. D.C. series motor

5688. Three point starter can be used for______________?
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A. series motor only

B. shunt motor only

C. compound motor only

D. both shunt and compound motor
5689. Sparking, is discouraged in a D.C. motor because_____________?
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A. it increases the input power con-sumption

B. commutator gets damaged

C. both A. and B.

D. none of the above

5690. Which D.C. motor has got maximum self loading property?
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A. Differentially compounded motor

B. Cumulatively compounded motor

C. Series motor

D. Shunt motor

5691. D.C. generators are normally designed for maximum efficiency around_____________?
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A. rated voltage

B. full-load

C. rated r.p.m.

D. all of the above

5692. In variable speed motor___________?
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A. none of the above is correct

B. a stronger 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. a weaker commutating field is needed at low speed than at high speed
5693. Ward-Leonard control is basically a____________?
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A. voltage control method

B. field control method

C. armature resistance control method

D. field divertor method

5694. The ratio of starting torque to full-load torque is least in case of____________?
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A. shunt motors

B. none of the above

C. series motors

D. compound motors

5695. The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is______________?
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A. 0.5

B. 4

C. 1

D. 2

5696. In case of D.C. shunt motors the speed is dependent on back e.m.f. only because____________?
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A. flux is practically constant in D:C. shunt motors

B. back e.m.f. is equal to armature drop

C. flux is proportional to armature current

D. armature drop is negligible

5697. Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be_____________?
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A. differentially compounded

B. level compounded

C. cumulatively compounded

D. under compounded

5698. The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is______________?
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A. 2.36%

B. 6.77%

C. 8.84%

D. 4.76%
5699. As -the load is increased the speed of D.C. shunt motor will____________?
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A. increase proportionately

B. remains unchanged

C. increase slightly

D. reduce slightly
5700. Sparking at the commutator of a D.C. motor may result in____________?
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A. increased power consumption

B. all of the above

C. damage to commutator segments

D. damage to commutator insulation