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
851. In a commutator_____________?
comments icon0

A. copper is harder than mica

B. none of the above

C. mica and copper are equally hard

D. mica is harder than copper
852. Armature coil is short circuited by brushes when it lies_____________?
comments icon0

A. in none of the above positions

B. along neutral axis

C. along field axis

D. in any of the above positions

853. Usually wide and sensitive speed control is desired in case of____________?
comments icon0

A. steel rolling mills

B. centrifugal pumps

C. colliery winders

D. elevators

854. For a D.C. generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f___________ ?
comments icon0

A. Depends on other features of design

B. Either of A. and B. above

C. Lap winding

D. Wave winding
855. Which D.C. motor is generally preferred for cranes and hoists ?
comments icon0

A. Shunt motor

B. Cumulatively compounded motor

C. Differentially compounded motor

D. Series motor
856. A D.C. welding generator has____________?
comments icon0

A. duplex winding

B. any of the above

C. lap winding

D. wave moving

857. A three point starter is considered suitable for______________?
comments icon0

A. shunt, compound and series motors

B. all D.C. motors

C. shunt motors

D. shunt as well as compound motors
858. A D.C. generator works on the principle of____________?
comments icon0
A. Faradays law of electromagnetic induction

B. Ohms law

C. Lenzs law

D. none of the above

859. Which one of the following is not the function of pole shoes in a D.C. machine ?
comments icon0

A. To spread out flux for better uniformity

B. To reduce the reluctance of the magnetic path

C. To reduce eddy current loss

D. To support the field coils

860. In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilized is called____________?
comments icon0

A. stator

B. rotor

C. field

D. armature
861. In case of conductively compensated D.C. series motors, the compensating winding is provided______________?
comments icon0

A. in parallel with field winding

B. in series with armature winding

C. as separately wound unit

D. in parallel with armature winding

862. In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralised by all of the following except______________?
comments icon0
A. dummy coils

B. interpoles

C. shifting of axis of brushes

D. compensating winding

863. D.C. series generator is used_________________?
comments icon0

A. to supply traction load

B. for none of the above purpose

C. to supply industrial load at constant voltage

D. voltage at the toad end of the feeder
864. With the increase in temperature, the speed of DC shunt motor____________?
comments icon0
A. increases

B. none of the above

C. decreases.

D. remain same

865. The condition for maximum power in case of D.C. motor is______________?
comments icon0

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

866. The armature voltage control of D.C. motor provides____________?
comments icon0

A. constant current drive

B. constant voltage drive

C. constant torque drive

D. none of the above

867. In which of the following device the generated emf and armature current are in the opposite directions?
comments icon0

A. dc generator

B. transformer

C. dc motor

D. all of the above

868. The plugging gives the____________?
comments icon0
A. highest torque braking

B. zero torque braking

C. smallest torque braking

D. none of the above

869. If a D.C. motor designed for 40C ambient temperature is to be used for 50C ambient temperature, then the motor_____________?
comments icon0

A. can be used for 50C ambient temperature also

B. of lower H.P. should be selected

C. of higher H.P. should be selected

D. is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor
870. Magnetic field in a D.C. generator is produced by_______________?
comments icon0
A. electromagnets

B. permanent magnets

C. both A. and B.

D. none of the above

871. A direct on line starter is used: for starting motors___________?
comments icon0

A. up to 10 H.P

B. up to 20 H.P

C. up to 5 H.P

D. up to 15 H.P

872. If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will_________?
comments icon0
A. increase

B. decrease

C. become zero

D. remain same

873. A separately excited generator as compared to a self-excited generator_____________?
comments icon0

A. is more stable

B. is amenable to better voltage control

C. has all above features

D. has exciting current independent of load current

874. Which of the following loss in a D.C. generator is dissipated in the form of heat?
comments icon0

A. Copper loss

B. Mechanical loss

C. All of the above

D. Core loss

875. In D.C. generators, lap winding is used for______________?
comments icon0

A. high voltage, high current

B. low voltage, low current

C. high voltage, low current

D. low voltage, high current
876. The shaft of an induction motor is made of_____________?
comments icon0

A. stainless steel

B. cast iron

C. carbon steel

D. high speed steel

877. In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when____________?
comments icon0
A. number of poles is 2

B. number of poles is 4

C. r.p.m. is more than 300

D. r.p.m. is less than 300

878. In a D.C. generator the ripples in the direct e.m.f. generated are reduced by_____________?
comments icon0

A. using conductor of annealed copper

B. using equiliser rings

C. using carbon brushes of superior quality

D. using commutator with large number of segments

879. What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
comments icon0

A. The motor will run noisy

B. The armature may burn

C. The motor will stop

D. The motor will continue to run

880. Number of tappings for each equalizer ring is equal to_____________?
comments icon0

A. number of parallel paths

B. number of commutator segments

C. number of poles

D. number of pole pairs
881. Eddy currents are induced in the pole shoes of a D.C. machine due to______________?
comments icon0
A. relative rotation between field and armature

B. oscillating magnetic field

C. pulsating magnetic flux

D. all above

882. In case of D.C. shunt motors the speed is dependent on back e.m.f. only because____________?
comments icon0

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

B. flux is proportional to armature current

C. flux is practically constant in D:C. shunt motors

D. armature drop is negligible

883. In D.C. generators, the cause of rapid brush wear may be___________?
comments icon0

A. severe sparking

B. rough commutator surface

C. imperfect contact

D. any of the above
884. Which of the following method of speed control of D.C. machine will offer minimum efficiency ?
comments icon0

A. Field control method

B. Armature control method

C. Voltage control method

D. All above methods

885. Which of the following loss in a D.C. generator varies significantly with the load current ?
comments icon0
A. Armature copper loss

B. None of the above

C. Windage loss

D. Field copper loss

886. The e.m.f. generated by a shunt wound D.C. generator isE. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be_______________?
comments icon0

A. E/2

B. E

C. 2E

D. slightly less than E

887. The following constitute short-circuit in the armature winding.
comments icon0
A. All of the above

B. Two of more turns of the same coil getting grounded

C. Insulation failure between two commutator bars

D. Insulation failure between two turns of a coil

888. A D.C. generator can be considered as____________?
comments icon0

A. rectifier

B. primemover

C. rotating amplifier

D. power pump

889. Two generators A and B have 6-poles each. Generator A has wave wound armature while generator B has lap wound armature. The ratio of the induced e.m.f. is generator A and B will be_______________?
comments icon0

A. 3:02

B. 2:03

C. 3 : 1

D. 1:03

890. Starters are used with D.C. motors because______________?
comments icon0

A. these motors are not self-starting

B. these motors have high starting torque

C. back e.m.f. of these motors is zero initially

D. to restrict armature current as there is no back e.m.f. while starting
891. Regenerative method of braking is based on that___________?
comments icon0

A. back e.m.f. is less than the applied voltage

B. none of the above

C. back e.m.f. is equal to the applied voltage

D. back e.m.f. of rotor is more than the applied voltage

892. Following energized winding of a D.C. machine should not be opened as it would produce high inductive voltage which may be dangerous to personnel and may cause its own insulation failure.
comments icon0
A. Shunt field

B. Compensating field

C. Inter pole field

D. Series field

893. Speed control by Ward Leonard method gives uniform speed variation_____________?
comments icon0

A. in one direction

B. in both directions

C. below normal speed only

D. above normal speed only

894. If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking?
comments icon0

A. dynamic braking

B. any of the above

C. none of the above

D. regenerative

E. plugging
895. A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly_______________?
comments icon0
A. 240 V

B. 150 V

C. 290 V

D. 175 V

896. Lap winding is composed of_____________?
comments icon0

A. that even number which is exact multiple of poles + 2

B. that even number which is exact multiple of poles

C. any odd number of conductors

D. any even number of conductors
897. The purpose of providing dummy coils in a generator is____________?
comments icon0

A. to enhance flux density

B. to reduce eddy current losses

C. to provide mechanical balance for the rotor

D. to amplify voltage

898. For which of the following applications a D.C. motor is preferred over an A.C. motor ?
comments icon0

A. Low speed operation

B. High speed operation

C. Variable speed operation

D. Fixed speed operation

899. For a D.C. machines laboratory following type of D.C. supply will be suitable___________?
comments icon0

A. mercury are rectifier

B. induction motor D.C. generator set

C. synchronous motor D.C. generator set

D. rotary converter

900. In variable speed motor___________?
comments icon0

A. a stronger commutating field is needed at low speed than at high speed

B. none of the above is correct

C. a weaker commutating field is needed at low speed than at high speed

D. same commutating field is needed at low speed than at high speed