1000+ Electrical Circuits MCQ for RRB ALP [Solved]

1. The power factor of a certain circuit in which the voltage lags behind the current is 80 %. To increase the power to 100 %a it is necessary to add ___ to the circuit.
A. Inductance
B. Capacitance
C. Resistance
D. Impedance
Answer : A

2. Electron flow assumes charges flow from
A. Negative to positive
B. Negative to negative
C. Positive to negative
D. Positive to positive
Answer : A

3. What is the rms value of a square wave?
A. Equals its peak value
B. Equals its peak-to-peak value
C. Peak divided by square root of two
D. Peak divided by pi
Answer : A

4. In a circuita an active element is one which
A. Supplies energy
B. Receives energy
C. Both supplies and receives energy
D. Amplifies signal
Answer : A

5. Rationalizing the denominator of a complex number means
A. Eliminating the j component in the denominator
B. Adding j component in the denominator
C. Eliminating the j component in the numerator
D. Adding j component in the numerator
Answer : A

6. What maximum voltage can be applied across the capacitor of time?
A. Working voltage
B. Surge voltage
C. Stray voltage
D. Peak voltage
Answer : B

7. If an emf in circuit A produces a current in circuit Ba then the same emf in circuit Bproduces the same current in circuit ? this theorem is known as
A. Maximum power transfer theorem
B. Millman�s theorem
C. Reciprocity theorem
D. Norton�s theorem
Answer : C

8. Barium-strontium titanite dielectric material is also called
A. Ceramic
B. Polyster
C. Electrolytic
D. Bakelite
Answer : A

9. The potential gradient in a cable is maximum in
A. Conductor
B. Outer sheath
C. Insulation
D. Uniformly all over
Answer : A

10. An ac series circuit is composed of a resistance of 20 a inductive reactance of 40 a and a capacitive reactance of 15 . If a current of 1 ampere is flowinga what is the applied voltage
A. 320 V
B. 32 V
C. 220 V
D. 22 V
Answer : B

11. In a complex number 5 + j 10a 10 is called ___ part.
A. Imaginary
B. Real
C. Conjugate
D. Integer
Answer : A

12. The current is ____ times the maximum current at half-power points of a resonance curve.
A.
B.
C.
D.
Answer : A

13. The rms value of a triangular or sawtooth waveform is ___ tim value.
A.
B.
C.
D.
Answer : A

14. What is the hot resistance of a 100 Wa 220 V incandescent lamp?
A.
B.
C.
D.
Answer : C

15. A capacitor of 0.5 F charged to 220 V is connected across an uncharged 0.5 F capacitor. What is the voltage across each capacitor?
A. 220 V
B. 150 V
C. 110 V
D. 22 V
Answer : C

16. The capacitance of a capacitor is ___ relative permittivity.
A. Directly proportional to
B. Inversely proportional to
C. Equal to
D. Inversely proportional to the square of
Answer : A

17. A capacitor opposes change in
A. Voltage
B. Current
C. Voltage and current
D. Neither voltage nor current
Answer : A

18. The voltage cannot be exactly in phase with the current in a circuit that contains
A. Only capacitance
B. Only resistance
C. Inductance and capacitance
D. Inductancea capacitance and resistance
Answer : A

19. If two equal resistances connected in series across a certain supply are now connected in parallel across the same supplya the power produced will be _____ that of series connection
A. One-half
B. One-fourth
C. Two times
D. Four times
Answer : D

20. Which of the following is not a factor affecting dielectric strength?
A. Mass
B. Moisture content
C. Temperature
D. Thickness
Answer : A

21. The charging of a capacitor through a resistance obeys
A. Exponential law
B. Logarithmic law
C. Linear law
D. Square law
Answer : A

22. What can be used to estimate resonant frequency and to find reactance at any frequency for any value of capacitor or inductor?
A. Smith chart
B. Reactance chart
C. Impedance chart
D. Resonance chart
Answer : B

23. What is the most convenient way of achieving large capacitance?
A. By using multiplate construction
B. By using air as dielectric
C. By decreasing distance between plates
D. By using dielectric of low permittivity
Answer : A

24. Which of the following does not affect resistance?
A. Resistivity
B. Cross-sectional area
C. Mass
D. Length
Answer : C

25. If three 9 mH inductors are connected in parallel without mutual inductance then the total i nductance is
A. 3 mH
B. 9 mH
C. 27mH
D. 18 mH
Answer : A

26. Refers specifically to steady state values of quantities in ac circuits which are complex numbers.
A. Domain
B. Scalar quantity
C. Vector quantity
D. Phasor quantity
Answer : D

27. What is the resonant frequency of a circuit when L of 25 microhenrys and C of 10 picofarads are in parallel?
A. 10.1 kHz
B. 10.1 MHz
C. 101 MHz
D. 101 kHz
Answer : B

28. What is the other name of relative permittivity?
A. Dielectric strength
B. Potential gradient
C. Breakdown voltage
D. Specific inductance capacity
Answer : D

29. The reason why alternating current can induce voltage is
A. It has high peak value
B. It has a stronger magnetic field than direct current
C. It has a constant magnetic field
D. It has a varying magnetic field
Answer : D

30. Which of the following combination of length and cross-sectional area will give a certain volume of copper the least resistance?
A. 2L and1/2 A
B. Does not matter because the volume of copper remains the same
C. L and A
D. ½ L and 2 A
Answer : D

31. A linear circuit is one whose parameters
A. Change with change in voltage
B. Change with change in current
C. Do not change with voltage and current
D. Change with change in voltage and current
Answer : C

32. Which of the following has a positive temperature coefficient?
A. Mica
B. Manganin
C. Silicon
D. Carbon
Answer : B

33. What does a capacitor store?
A. Voltage
B. Charge
C. Current
D. Power
Answer : B

34. What is a rotating vector whose projection can represent either current or voltage in an ac circuit?
A. Polar diagram
B. Scalar quantity
C. Velocity
D. Phasor
Answer : D

35. In adding or subtracting phasor quantitiesa ___ form is the most convenient.
A. Polar
B. Rectangular
C. Trigonometric
D. Exponential
Answer : B

36. A capacitive load always has a ______ power facto
A. Leading
B. Lagging
C. Zero
D. Unity
Answer : A

37. Of the equivalent combination of unitsa which one is not equal to watt?
A. 2/V
B. AV
C. A2
D. J/s
Answer : A

38. What theorem is generally used in the analysis of vacuum tubes?
A. Superposition theorem
B. Millman�s theorem
C. Thevenin�s theorem
D. Norton�s theorem
Answer : C

39. In a rectangular wavea the form factor is
A.
B.
C.
D.
Answer : C

40. Which of the following capacitors has the highest cost per F?
A. Plastic
B. Air
C. Mica
D. Electrolytic
Answer : D

41. Which of the following is also known as antiresonant circuit?
A. Parallel resonant circuit
B. Series resonant circuit
C. Tuned circuit
D. Tank circuit
Answer : A

42. An open inductor has
A. Zero resistance and infinite inductance
B. Infinite resistance and zero inductance
C. Infinite resistance and infinite inductance
D. Zero resistance and zero inductance
Answer : B

43. What is the total resistance of a two equal valued resistors in series?
A. The difference of both
B. The product of both
C. Twice as one
D. The sum of their reciprocals
Answer : C

44. In a series RLCcircuit
A. The current lags VLby 90�
B. The current leads VLby 90�
C. XL leads Xcby 90�
D. Z = jXL at resonance
Answer : A

45. The area of capacitor plates increases two timesa then its capacitance
A. Increases two times
B. Increases four times
C. Decreases two times
D. Decreases four times
Answer : A

46. An intermittent and non-symmetrical alternating current like that obtained from the secondary winding of an induction coil
A. Faradic current
B. Transient ac current
C. Inductive current
D. Capacitive current
Answer : A

47. Which of the following is the statement of Ohm�s law?
A. Electric current is directly proportional to both voltage and resistance
B. Electric current varies directly as the voltage and inversely as the resistance
C. Electrical power is directly proportional to the resistance and inversely as the current squared
D. Electrical power is directly proportional to both voltage squared and the resistance
Answer : B

48. What is the peak factor of a triangular wave?
A.
B.
C.
D.
Answer : B

49. For a series circuita the higher the quality factor
A. The greater the bandwidth
B. The narrower the passband
C. The broader the resonance curve
D. The wider the passband
Answer : B

50. What is the total capacitance of 10 capacitorsa each of 20 F in series?
A. 200 F
B. 2 F
C. 100 F
D. 0.5 F
Answer : B