Electrical engineering MCQ Quiz Hub

1. The four arms of an AC bridge network are as follows: Arm AB: unknown impedance Arm BC: standard capacitor C2 of 1000pf Arm CD: a non-inductive resistance of R of 100 Ω in parallel to a capacitor of 0.01 μF Arm DA: a non-inductive resistance of 1000 Ω The supply frequency is 50 Hz and connected across terminals B and D. If the bridge is balanced with the above value, determine the value of unknown Impedance.
10 kΩ
100 kΩ
250 kΩ
20 kΩ

2. Two coils are having self-inductance of 5 mH and 10 mH and a mutual inductance of 0.5 mH in a differential connection. The equivalent inductance of the combination is ___________
14 mH
5.85 mH
6 mH
6.15 mH

3. When two coupled coils of equal self-inductance are connected in series in one way the net inductance is 20 mH and when they are connected in the other way, the net inductance is 12 mH. The maximum value of net inductance when they are connected in parallel is __________
2 mH
5 mH
4 mH
6 mH

4. A circuit resonates at 1 MHz It also has a Q of 100. Bandwidth between half power points is _____________
10 kHz
100 kHz
10 Hz
100 Hz

5. Two resistances 100 ± 5Ω and 150 ± 15Ω are connected in series. If the error is specified as standard deviations, the resultant error will be ________________
±10 Ω
±10.6 Ω
±15.8 Ω
±20 Ω

6. A coil is designed for high Q performance at a rated voltage and a specified frequency. If the frequency is made twice the original and the coil is operated at the same rated voltage, then the Q factor will be affected as ____________
Q is halved
Q remains unchanged
Q is doubled
Q increases or decreases but magnitude cannot be measured

7. A coil is designed for high Q performance at a rated voltage and a specified frequency. If the frequency is made twice the original and the coil is operated at the same rated voltage, then the active power P will be affected as ____________
P is halved
P remains unchanged
P is doubled
P decreases 4 times

8. A (350 A/7A), 50 Hz current transformer has a primary bar. The secondary has a pure resistance of 1 Ω. It also draws a current of 5 A. The magnetic core requires 350 AT for magnetization. Find the percentage ratio error.
10.56
-28.57
11.80
-11.80

9. The CT supplies current to the current coil of a wattmeter power factor meter, energy meter and, an ammeter. These are connected as?
All coils in parallel
All coils in series
Series-parallel connection with two in each arm
Series-parallel connection with one in each arm

10. A current of [2 + 2–√sin (314t + 30) + 22–√cos (952t +45)] is measured with a thermocouple type, 5A full scale, class 1 meter. The meter reading would lie in the range?
5 A ± 1 %
(2 + 32–√) A ± 1%
3 A ± 1.7 %
2 A ± 2.5 %

11. The relation between the Q factor of a coil measured by the Q Meter and the actual Q of the coil is _________
Equal to
Same but somewhat lesser than
Same but somewhat higher than
Not equal to

12. The power generated by a machine increases _____________ percent from single phase to two phase.
40.4
41.4
42.4
43.4

13. The percentage of power increased from single phase to three phase is?
50
100
150
200

14. When the power factor is __________ the power becomes zero 100 times a second in a 50Hz supply.
0
1
2
3

15. Which motors are called self-starting motors?
single phase
two phase
three phase
four phase

16. In three phase system, the three voltages (currents) differ in phase by __________electrical degrees from each other in a particular sequence.
30
60
90
120

17. In three phase system at any given instant, the algebraic sum of three voltages must be?
0
1
2
3

18. Phase sequence depends on the _________________
field
rotation of the field
armature
rotation of the armature

19. In a three phase alternator, there are __________ independent phase windings or coils.
1
2
3
4

20. Each coil in three phase alternator has ________________ number of terminals.
2
4
6
8

21. In wye or star connection _____________ of the three phases are joined together within the alternator.
similar ends
opposite ends
one similar end, two opposite ends
one opposite end, two opposite ends

22. The voltage between __________ and ___________ is called phase voltage.
line and line
line and reference
neutral point and reference
line and neutral point

23. The voltage between ______________ is called line voltage.
line and neutral point
line and reference
line and line
neutral point and reference

24. In the Delta or Mesh connection, there will be __________ number of common terminals.
1
2
3
0

25. A balanced delta-connected load of (2+j3) Ω per phase is connected to a balanced three-phase 440V supply. The phase current is 10A. Find the total active power.
7.26W
726W
7260W
72.6W

26. A balanced delta-connected load of (2+j3) Ω per phase is connected to a balanced three-phase 440V supply. The phase current is 10A. Find the apparent power.
10955.67 VAR
10.95567 VAR
109.5567 VAR
1.095567 VAR

27. In a delta-connected load, the relation between line voltage and the phase voltage is?
line voltage > phase voltage
line voltage < phase voltage
line voltage = phase voltage
line voltage >= phase voltage

28. Determine the power (kW) drawn by the load.
21
22
23
24

29. If the system is a three-wire system, the currents flowing towards the load in the three lines must add to ___ at any given instant.
1
2
3
zero

30. The wattmeter method is used to measure power in a three-phase load. The wattmeter readings are 400W and -35W. Calculate the total active power.
360
365
370
375

31. The wattmeter method is used to measure power in a three-phase load. The wattmeter readings are 400W and -35W. Find the power factor.
0.43
0.53
0.63
0.73

32. The wattmeter method is used to measure power in a three-phase load. The wattmeter readings are 400W and -35W. Find the reactive power.
751.44
752.44
753.44
754.44

33. The input power to a three-phase load is 10kW at 0.8 Pf. Two watt meters are connected to measure the power. Find the reading of higher reading wattmeter.
7.165
6.165
6.165
4.165

34. The input power to a three-phase load is 10kW at 0.8 Pf. Two watt meters are connected to measure the power. Find the reading of lower reading wattmeter.
1.835
2.835
3.835
4.835

35. The readings of the two watt meters used to measure power in a capacitive load are -3000W and 8000W respectively. Calculate the input power. Assume RYB sequence.
5
50
500
5000

36. The readings of the two watt meters used to measure power in a capacitive load are -3000W and 8000W respectively. Find the power factor.
0.25
0.5
0.75
1

37. A single wattmeter is connected to measure the reactive power of a three-phase, three-wire balanced load. The line current is 17A and the line voltage is 440V. Calculate the power factor of the load if the reading of the wattmeter is 4488 VAR.
0.6
0.8
1
1.2

38. The expression of current in R-L circuit is?
i=(V/R)(1+exp⁡((R/L)t))
i=-(V/R)(1-exp⁡((R/L)t))
i=-(V/R)(1+exp⁡((R/L)t))
i=(V/R)(1-exp⁡((R/L)t))

39. The steady state part in the expression of current in the R-L circuit is?
(V/R)(exp⁡((R/L)t))
(V/R)(-exp⁡((R/L)t))
V/R
R/V

40. In the expression of current in the R-L circuit the transient part is?
R/V
(V/R)(-exp⁡((R/L)t))
(V/R)(exp⁡((R/L)t))
V/R

41. The value of the time constant in the R-L circuit is?
L/R
R/L
R
L

42. After how many time constants, the transient part reaches more than 99 percent of its final value?
2
3
4
5

43. The expression of current in R-C circuit is?
i=(V/R)exp⁡(t/RC)
i=(V/R)exp⁡(-t/RC)
i=(V/R)-exp(⁡t/RC)
i=(V/R)-exp⁡(-t/RC)

44. In an R-C circuit, when the switch is closed, the response ____________
do not vary with time
decays with time
rises with time
first increases and then decreases

45. The time constant of an R-C circuit is?
RC
R/C
R
C

46. If the roots of an equation are real and unequal, then the response will be?
critically damped
under damped
over damped
damped

47. If the roots of an equation are complex conjugate, then the response will be?
over damped
critically damped
damped
under damped

48. If the roots of an equation are real and equal, then the response will be?
over damped
damped
critically damped
under damped

49. Laplace transform changes the ____ domain function to the _____ domain function.
time, time
time, frequency
frequency, time
frequency, frequency

50. The unit step is not defined at t =?
0
1
2
3