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
701. According to Flemings right-hand rule for finding the direction of induced e.m.f., when middle finger points in the direction of induced e.m.f., forefinger will point in the direction of____________?
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A. motion of conductor

B. none of the above

C. either of the above

D. lines of force
702. The starting resistance of a D.C. motor is generally_______________?
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A. low

B. 1000 Q

C. infinitely large

D. around 500 Q

703. If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens__________?
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A. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed

B. nothing will happen to the motor

C. this will make armature to take heavy current, possibly burning it

704. Iron losses in a D.C. machine are independent of variations in_____________?
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A. speed

B. load

C. speed and voltage

D. voltage

705. A shunt generator can self-excite:_________________?
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A. none

B. only if the resistance of the field circuit is less than critical value

C. irrespective of the value of the resistance in the field circuit

D. only if the resistance of the field circuit is greater than critical value

706. If a D.C. generator fails to build up the probable cause could not be_____________?
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A. imperfect brush contact

B. no residual magnetism in the generator

C. faulty shunt connections tending to reduce the residual magnetism

D. field resistance less than the critical resistance
707. In the D.C. motor the iron losses occur in____________?
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A. the field

B. the commutator

C. the armature

D. the brushes

708. The current drawn by the armature of D.C. motor is directly proportional to__________?
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A. the speed of the motor

B. none of the above

C. the torque required

D. the voltage across the terminals

709. The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage____________?
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A. will be less than 250 V

B. none of the above

C. may be greater or less than 250 V

D. will always be 250 V

710. Following motor is used where high starting torque and wide speed range control is required?
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A. Synchronous motor

B. None of the above

C. Single phase capacitor start

D. D.C. motor

E. Induction motor

711. Iron losses in a D.C. machine are independent of variations in______________?
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A. speed

B. speed and voltage

C. load

D. voltage

712. Copper brushes in D.C. machine are used_____________?
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A. where low voltage and high currents are involved

B. where high voltage and small cur-rents are involved

C. in both of the above cases

D. in none of the above cases

713. Permeance is the reciprocal of______________?
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A. resistance

B. ampere-turns

C. flux density

D. reluctance
714. The bearings used to support the rotor shafts are generally______________?
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A. bush bearings

B. needle bearings

C. ball bearings

D. magnetic bearmgs

715. The purpose of retardation test on D.C. shunt machines is to find out____________?
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A. field copper losses

B. eddy current losses

C. stray losses

D. windage losses

716. Interpole flux should be sufficient to_____________?
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A. neutralise the commutating self induced e.m.f.

B. neutralise the armature reaction flux

C. neutralise both the armature reaction flux as well as commutating e.m.f. induced in the coil

D. perform none of the above functions

717. D.C. generators are normally designed for maximum efficiency around_____________?
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A. full-load

B. all of the above

C. rated r.p.m.

D. rated voltage

718. In D.C. generators, the brushes on commutator remain in contact with conductors which_________________?
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A. are farthest from the poles

B. lie under south pole

C. lie under interpolar region

D. lie under north pole

719. The terminal voltage of a series generator is 150 V when the load current is 5 A. If the load current is increased to 10 A, the terminal voltage will be____________?
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A. less than 150 V

B. 150 V

C. greater than 150 V

D. none of the above

720. Which of the following generator will have negligible terminal voltage while running on no-load?
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A. Shunt generator

B. Compound generator

C. Separately excited generator

D. Series generator
721. A cumulatively compounded long shunt generator when operating as a motor would be____________?
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A. deferentially compounded long shunt

B. cumulatively compounded short shunt

C. differentially compounded short shunt

D. cumulatively compounded long shunt

722. Shunt generators are most suited for stable parallel operation because of their______________?
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A. drooping voltage characteristics

B. rising voltage characteristics

C. linear voltage characteristics

D. identical voltage characteristics

723. The material for commutator brushes is generally_______________?
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A. mica

B. copper

C. carbon

D. cast iron

724. For starting a D.C. motor a starter is required because___________?
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A. none of the above

B. it limits the starting current to a safe value

C. it limits the speed of the motor

D. it starts the motor

725. 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
726. Ward-Leonard control is basically a____________?
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A. voltage control method

B. armature resistance control method

C. field control method

D. field divertor method

727. If I2 be the armature current, then speed of a D.C. shunt motor is_______________?
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A. independent of Ia

B. varies as (Ia)

C. proportional to la

D. varies as la

728. In D.C. generators the pole shoes are fastened to the pole core by_____________?
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A. counter sunk screws

B. brazing

C. rivets

D. welding

729. If the load on a DC shunt motor is increases, its speed is slightly reduced due to______________?
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A. decrease in back emf

B. increase in flux

C. increase in armature current

D. decrease in reactance

730. Ward Leonard method of speed control is basically a______________?
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A. armature controlled method

B. frequency control method

C. field control method

D. field diverter

731. One D.C. motor drives another D.C. motor. The second D.C. motor when excited and driven_______________?
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A. does not run as a generator

B. runs as a generator

C. also runs as a motor comes to stop after sometime

732. Armature reaction in dc motor results___________?
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A. open circuit

B. short circuit

C. increase in speed

D. decrease in speed

733. Equilizer rings are required in case armature is_______________?
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A. wave wound

B. duplex wound

C. lap wound

D. delta wound

734. Which of the following generators will be preferred if they are required to be run in parallel?
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A. Shunt generators

B. Compound generators

C. Series generators

D. None of the above

735. In a level compounded D.C. generator, full load terminal voltage is______________?
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A. less than no-load terminal voltage

B. negligibly low

C. equal to no-load terminal voltage

D. more than no-load terminal voltage

736. Flemings right-hand rule regarding direction of induced e.m.f., correlates__________?
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A. magnetic field strength, induced voltage and current

B. magnetic flux, direction of force and direction of motion of conductor

C. magnetic flux, direction of current flow and resultant force

D. magnetic flux, direction of motion and the direction of e.m.f. induced
737. Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be_____________________?
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A. 265 V

B. 267.5 V

C. 270 V

D. 257.4 V

738. For the parallel operation of two or more D.C. compound generators, we should ensure that_______________?
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A. all the series fields should be run in parallel by means of equilizer connection

B. series fields of all generators should be either on positive side or negative side of the armature

C. polarity of incoming generator should be same as that of bus bar

D. all conditions mentioned above should be satisfied

E. voltage of the incoming generator should be same as that of bus bar

739. D.C. generators are installed near the load centres to reduce_____________?
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A. corona losses

B. iron losses

C. line losses

D. sparking

740. 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. 1

B. 0.5

C. 4

D. 2

741. An exciter for a turbo generator is a_____________?
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A. compound generator

B. series generator

C. shunt generator

D. separately excited generator

742. In a D.C. generator:___________________?
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A. external characteristic = magnetisation characteristic ohmic drop armature reaction

B. internal characteristic = magnetisation characteristic ohmic drop

C. external resistance = internal char-acteristic armature reaction

D. magnetisation characteristic = external characteristic

743. As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit____________________?
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A. a resistance is connected in series with armature

B. a resistance is connected parallel to the armature

C. armature is temporarily open circuited

D. a high value resistor is connected across the field winding

744. The armature voltage control of D.C. motor provides_____________?
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A. constant current drive

B. constant voltage drive

C. none of the above

D. constant torque drive
745. Compensating windings are used in D.C. generators______________?
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A. none of the above

B. to neutralise the cross-magnetising effect of the armature reaction

C. mainly to reduce the eddy currents by providing local short-circuits

D. to provide path for the circulation of cooling air

746. The critical resistance of the D.C. generator is the resistance of_____________?
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A. load

B. brushes

C. armature

D. field
747. The e.m.f. generated in a D.C. generator is directly proportional to____________?
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A. flux/pole

B. speed of armature

C. number of poles

D. all of the above

748. Satisfactory commutation of D.C. machines requires______________?
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A. brushes should be of proper grade and size

B. smooth, concentric commutator properly undercut

C. brushes should smoothly run in the holders

D. all of the above
749. When two D.C. series motors are connected in parallel, the resultant speed is____________?
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A. zero

B. loss than the normal speed

C. normal speed

D. more than the normal speed

750. As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately______________?
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A. 10 percent

B. 25 percent

C. 40 percent

D. 5 percent