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electrical engineering MCQs

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 Review each marked answer and report any item that may be outdated or unclear.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 generation 2. analog electronics 3. solid state switching circuits 4. parallel circuits 5. switchgear and protection 6. op amp circuits 7. transistor audio power amplifiers 8. electrostatics 9. heating and welding 10. multi stage transistor amplifiers 11. passive filters 12. network theorems 13. regulated d c power supply 14. a c fundamentals circuits and circuit theory 15. electromagnetic induction 16. power electronics 17. magnetism and electromagnetism 18. transformers 19. modulation and demodulation 20. d c generators 21. semiconductor theory 22. single phase induction motors 23. semiconductor diode 24. hybrid parameters 25. digital electronics 26. oscillators 27. earthing or grounding 28. single stage transistor amplifiers 29. d c motors 30. transistor biasing 31. amplifiers with negative feedback 32. basic electrical 33. electronic instruments 34. synchronous motors 35. field effect transistors fet 36. magnetic circuit 37. control systems 38. industrial drives 39. power generation 40. series parallel circuits 41. transistor tuned amplifiers 42. electrical engineering materials 43. rectifiers and converters 44. integrated circuits 45. scr silicon controlled rectifiers 46. cables 47. polyphase induction motors 48. measurement and instrumentation 49. transistors 50. electrical machine design 51. electrolysis and storage of batteries 52. electric traction 53. transmission and distribution

Electrical Engineering MCQs: Study Guide

Electrical engineering objective tests cover a wide range of circuit, machine, electronics, power and measurement concepts. Formula recall works best when paired with units, assumptions and a quick sense-check of the result.

Topics to revise

Circuit theory
Electrical machines
Power systems
Measurements
Control systems
Analog electronics
Digital electronics
Power electronics

How to prepare

Create a formula sheet by topic, solve short numerical problems without looking at options, and check dimensions before selecting an answer. Alternate conceptual questions with calculations and focus review on repeated error types.

Common questions

Should I solve the calculation before reading options?

When practical, yes. Independent calculation reduces the chance of being led by a plausible distractor.

How should formulas be revised?

Store each formula with its units, assumptions and one worked example rather than memorising symbols alone.

1. SITH is also known as___________?
0

A. None of these

B. Silicon controlled rectifier

C. Filled controlled rectifier

D. Filled controlled diode

2. SCRs are used in series to meet_______________?
0

A. low voltage demand

B. low current demand

C. high voltage demand

D. high current demand

3. As the breakdown voltage reached, the DIAC exhibits?
0

A. All of these

B. Voltage drop snaps back

C. Negative resistance characteristics

D. Goes into avalanche condition

4. Internal resistance of ideal current source is ?
0

A. finite

B. 100 ohms

C. zero

D. infinite

5. Which semiconductor device acts like a diode and two transistor?
0

A. Triac

B. SCR

C. Diac

D. UJT

A. Identical to line voltage in a VSI

B. Identical to line current in VSI

C. Identical to phase voltage in VSI

D. Identical to phase voltage in CSI

7. Thyristor is nothing but a____________?
0

A. Amplifier with higher gain

B. Amplifier with large current gain

C. Controlled switch

D. Controlled transistor

8. The voltage induced in an inductor is represented as,
0

A. ratio of the current through it to its inductance.

B. product of its inductance and current through it.

C. ratio of its inductance to the current through it.

D. product of its inductance and rate of change of current through it.

9. n a phase controlled 3 phase ac voltage controller, the harmonic present is__________?
0

A. 5th

B. 3rd

C. 2nd

D. 7th

10. Materials used in heat sink should have_____________?
0

A. large surface area

B. high thermal conductivity

C. high melting point

D. All of these

11. For swept frequency measurements, the input impedance of the mismatched transmission line would vary with frequency as the electrical length of the transmission line would
0

A. Remains same with change in frequency

B. Either A. or B.

C. Decrease with frequency

D. Increase with frequency

12. Which of following devices has highest di/dt and dv/dt capability?
0

A. GTO

B. SIT

C. SCR

D. SITH

13. Voltage commutation circuit can be converted into a current commutation by interchanging the positions of____________?
0

A. Capacitor and SCR

B. Inductor and capacitor

C. Diode and capacitor

D. Capacitor and load

14. In EMC signal, the source delivers maximum power to the input of transmission line when the transmission line input impedance
0

A. Greater than the source resistance

B. Is equal to the source resistance

C. None of these

D. Smaller than the source resistance

15. Which of the following is true about SIT?
0

A. SIT is a high power, low frequency device

B. SIT is a high power, high frequency device

C. SIT is a low power, high frequency device

D. SIT is a high power, high voltage device

16. In BJT, the forward biased base emitter junction inject holes from base to emitter, the holes_______?
0

A. Contribute to the collector current

B. Result in net current flow component into the base

C. Do not contribute to the collector current

D. Only (a) and (b)

E. Only (b) and (c)

17. During the commutation period in 3 phase converter, overlap time is_____________?
0

A. Dependent on the load current

B. Dependent on the voltage

C. Dependent on both the load current and load voltage behind the short circuit current

D. Independent on both the load current and load voltage

18. Under harmonic free load voltages, the 3 phase VSI_____________?
0

A. Does not contains fifth harmonic

B. Does not contains third harmonic

C. Does not contains seventh harmonic

D. Does not contains second harmonic

19. Power dissipation in ideal inductor is
0

A. Zero

B. Minimum

C. A finite value

D. Maximum

20. Which of following is normally ON device?
0

A. TRIAC

B. BJT

C. SIT

D. IGBT

21. In forward blocking mode of a thyristor________?
0

A. Junction J1, J3 is in reverse bias and J2 is in forward bias.

B. junction J2 is in reverse bias and J1, J3 is in forward bias.

C. Junction J1 and J2 is in forward bias and J3 is in reverse bias.

D. junction J3 is in forward bias and J1, J2 is in reverse bias.

22. For series connected SCRaEURs dynamic equalising circuit consists of___________?
0

A. Series R and diode with C across R

B. R and C in series but with diode across R

C. R and C in series but with diode across C

D. Series R and diode with C across R

23. During which time maximum conduction spreading take place in the thyristor during turn ON?
0

A. Same for every case

B. Rise time

C. Spread time

D. Delay time

24. The unit of resistivity is
0

A. ? / m.

B. ? / metre.

C. ?.

D. ? metre.

25. What may happen high dV / dt____________?
0

A. Unwanted turn ON

B. Breakdown of J2 junction

C. Both A and B

D. Anyone of these

26. An SCR has half cycle surge current rating of 3000 A for 50 Hz supply. One cycle surge current will be_____?
0

A. 1500 A.

B. 4242.64 A.

C. 2121.32 A.

D. 6000 A.

27. Delay time is defined by the interval when_______________?
0

A. all of these

B. gate current increases from 90 % to 100 % of its final value

C. anode current reaches 10 % from forward leakage current

D. anode voltage drops from 100 % to 90 % of its actual value

28. Dynamic equalizing circuit is used for________________?
0

A. equal division of voltage across each thyristor in parallel

B. equal division of current through each thyristor in parallel

C. equal division of current through each thyristor in series

D. equal division of voltage across each thyristor

29. 4 thyristors rated 200 V in series. The operating voltage of the string is 600 V. Derating factor of the string is_____________________?
0

A. 0.25

B. 0.75

C. 0.7

D. 0.2

30. Maximum di / dt in a SCR is________?
0

A. Directly proportional to Vm of supply voltage

B. Inversely proportional to Vm of supply voltage

C. Inversely proportional to L in the circuit

D. Both A and C

31. Gate circuit or triggering circuit of a thyristor is
0

A. high power circuit.

B. magnetic circuit.

C. may be low power or high power circuit

D. lower power circuit.

32. Switching frequency of SITH is____________?
0

A. 60 KHz

B. 10 KHz

C. 5 KHz

D. 100 KHz

33. In a 3 phase bridge rectifier the ripple frequency is _____________?
0

A. Three times the input frequency

B. Equal to the input frequency

C. Twice the input frequency

D. Six times the input frequency

34. How many coulombs of charge flow through a circuit carrying a current of 10 A in 1 minute?
0

A. 1200

B. 60

C. 10

D. 600

35. A power semiconductor may undergo damage due to____________?
0

A. Low dv/dt

B. High dv/dt

C. Low di/dt

D. High di/dt

36. What is the advantage of HRC fuses over Rewirable fuses?
0

A. High rupturing capacity

B. No ageing effect

C. All of the above

D. High speed operation

37. AC power in a load can be controlled by using____________?
0

A. Two SCRs in series

B. Three SCRs in series

C. Four SCRs in series

D. Two SCRs in parallel opposition

38. Under normal operating condition voltage clamping device offers impedance of_________?
0

A. zero value.

B. low value.

C. moderate value.

D. high value.

39. Leakage current flows through the thyristor in_________?
0

A. forward blocking mode

B. reverse blocking mode

C. both forward and reverse blocking mode

D. forward conduction mode

40. Rise time is defined by the interval when____________?
0

A. gate current rises from 90 % to 100 % of it final value

B. anode voltage drops from 90 % to 10 % of its initial value

C. anode current rises 10 % to 90 % of its final value

D. both B and C

41. Double fourier series analysis of PWM is_____________?
0

A. Two dimensional functions

B. All of these

C. Three dimensional functions

D. One dimensional functions

42. The maximum firing angle in the half wave controlled regulator is_____________?
0

A. 210 degree

B. 180 degree

C. 200 degree

D. 190 degree

43. A single phase full bridge inverter can operated in load commutation mode in case load consist of______?
0

A. RLC overdamped.

B. RLC critically damped

C. RL.

D. RLC underdamped.

44. A string of n parallel SCRs is operated at 72 KA, the rating of each SCR is 1 KA. If derating factor of the string is 0.1. value of n will be___________?
0

A. 70

B. 60

C. 90

D. 80

45. The typical value of SCR for modern alternator is____________?
0

A. 0.5.

B. 1.2.

C. 1.0.

D. 1.5.

46. If 1 A current flows in a circuit, the number of electrons flowing through this circuit is
0

A. 0.625 1019

B. 0.625 10-19

C. 1.6 1019

D. 1.6 10-19

47. If the gate voltage of an SCR is removed, then the_______________?
0

A. anode current increases

B. anode current does not decrease at all

C. cathode current increases

D. anode current decreases

48. A PNPN device having two gates is ___________?
0

A. Triac

B. Diac

C. BCS

D. SUS

49. Maximum power loss occurs during_________________?
0

A. rise time

B. spread time

C. all

D. delay time

50. A single phase ac dc converter is also known as____________?
0

A. inverter

B. rectifier

C. regulator

D. chopper

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