electrical engineering MCQs – Page 281

Practise multiple-choice questions from electrical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

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
5601. Starters are used with D.C. motors because______________?
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A. back e.m.f. of these motors is zero initially

B. these motors have high starting torque

C. to restrict armature current as there is no back e.m.f. while starting

D. these motors are not self-starting

5602. In D.C. shunt motors as load is reduced__________________?
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A. the speed will remain almost/constant

B. the speed will reduce

C. the speed will increase abruptly

D. the speed will increase in proportion to reduction in load

5603. D.C. series motors are used______________?
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A. where load changes frequently

B. where constant operating speed is needed

C. where load is constant

D. in none of the above situations
5604. The main disadvantage of the Ward-Leonard control method is______________?
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A. all of the above

B. high maintenance cost

C. low efficiency at Hght loads

D. high initial cost

5605. If the field winding resistance of a DC shunt motor is increases, its speed will____________?
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A. increases

B. none of the above

C. the field winding resistance of a DC shunt motor is increases, its speed will

D. remains same

E. decreases

5606. Which one of the following is not the function of pole shoes in a D.C. machine ?
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A. To reduce eddy current loss

B. To reduce the reluctance of the magnetic path

C. To spread out flux for better uniformity

D. To support the field coils

5607. In case-the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be______________?
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A. around 90%

B. anywhere between 75% and 90%

C. less than 50%

D. 100%

5608. Regenerative method of braking is based on that___________?
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A. none of the above

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

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

D. back e.m.f. is equal to the applied voltage
5609. Hopkinsons test on D.C. machines is conducted at_______________?
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A. no-load

B. full-load

C. part load

D. overload

5610. Which of the following test can be performed on DC series motor?
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A. Field test

B. Hopkinson test

C. Swinburne test

D. Brake test

5611. Which of the following loss in a D.C. generator is dissipated in the form of heat?
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A. Core loss

B. Mechanical loss

C. All of the above

D. Copper loss

5612. In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to
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A. none of the above

B. 10% of the previous value

C. 100% of the previous value

D. 50% of the previous value

E. 25% of the previous value
5613. The speed of a D.C. series motor is_____________?
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A. proportional to the armature current

B. proportional to field current

C. inversely proportional to the armature current

D. proportional to the square of the armature current

5614. Torque developed by a D.C. motor depends upon_____________?
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A. current flow through the conductors

B. radius of armature

C. magnetic field

D. active length of the conductor

E. all above factors

F. number of conductors

5615. The armature torque of the D.C. shunt motor is proportional to____________?
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A. field flux only

B. armature current only

C. both A. and B.

D. none of the above

5616. Which D.C. motor is generally preferred for cranes and hoists ?
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A. Shunt motor

B. Series motor

C. Differentially compounded motor

D. Cumulatively compounded motor

5617. A dc series motor should not be started on no load because it would___________?
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A. draw more current without producing sufficient torque

B. run at dangerously high speed

C. not develop starting torque

D. fail to start without load

5618. In D.C. machines the residual magnetism is of the order of_________________?
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A. 10 to 15 per cent

B. 20 to 25 per cent

C. 50 to 75 per cent

D. 2 to 3 per cent
5619. In a DC motor the inter-pole winding is connected in________________?
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A. parallel big field winding

B. parallel with armature winding

C. series with field winding

D. series speed armature winding
5620. For which of the following applications a D.C. motor is preferred over an A.C. motor ?
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A. High speed operation

B. Low speed operation

C. Variable speed operation

D. Fixed speed operation