Electrical Circuits MCQ Solved Paper for ESIC

1. If three 100-pF capacitors are connected in seriesa then the total capacitance is
A. 300 pF
B. 100 pF
C. 50 pF
D. 33.3 pF
Answer : D

2. Which of the following is the most popular waveform?
A. Sinusoidal
B. Square wave
C. Triangular
D. Sawtooth
Answer : A

3. Liquids that are good conductors because of ionization are called
A. Electrolytic
B. Bases
C. Acid
D. Electrolytes
Answer : D

4. 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

5. The internal resistance of an ideal voltage source is
A. Infinite
B. Equal to the load resistance
C. Zero
D. To be determined
Answer : C

6. 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

7. Inductive reactance applies only to sine waves because it
A. Increases with lower frequencies
B. Increases with lower inductance
C. Depends on the factor 2
D. Decreases with higher frequencies
Answer : C

8. A neon glow lamp used as a night light ionizes at approximately
A. 70 V
B. 80 V
C. 90 V
D. 100 V
Answer : A

9. A coil of inductance L has an inductive reactance of XLin an ac circuit in which the effective current is I. The coil is made from a superconducting material. The rate at which power is dissipated in the coil is
A.
B. I2XL
C. IXL
D. IXL2
Answer : A

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

11. If a coil has a Q of 10a it means that
A. The energy stored in the magnetic field of the coil is 10 times the energy wasted in its resistance
B. The energy wasted in its resistance is 10 times the energy stored in the magnetic field of the coil
C. It is a low Q coil
D. It is a high Q coil
Answer : A

12. A factor that states how much the resistance changes for a change in temperature?
A. Resistivity
B. Specific resistance
C. Coefficient of temperature change
D. Temperature coefficient of resistance
Answer : D

13. If resonant frequency is 10 kHz and quality factor is 50a then
A. Bandwidth is 200 Hz
B. XL= is 50a000
C. R is 50
D. XC= is 50a000
Answer : A

14. In a multiple capacitora the plate area is
A. Increased
B. The same
C. Decreased
D. Variable
Answer : A

15. A trimmer is a variable capacitor in which capacitance is varied by changing the
A. Number of plates
B. Dielectric
C. Distance between plates
D. Plate area
Answer : C

16. What is the reciprocal of quality factor?
A. Power factor
B. Reactive factor
C. Dissipation factor
D. 1/Q factor
Answer : C

17. The result of rust in electrical (wire) connection is
A. Inductance
B. Conductance
C. Impedance
D. Resistance
Answer : D

18. If the capacitance of mica capacitor is 5 times the capacitcitora then the relative permittivity of mica is
A.
B.
C.
D.
Answer : B

19. 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

20. 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

21. For multi-plate capacitora capacitance is proportional to
A. Number of plates less one(n ± 1)
B. Number of plates plus one(n + 1)
C. Number of plates less two(n - 2)
D. Number of plates (n)
Answer : A

22. The ratio of W/VA in an ac circuit means
A. Power factor
B. Reactive factor
C. Quality factor
D. Load factor
Answer : A

23. In liquids and gasesa ionization current results from a flow of
A. Positive or negative ions
B. Free electrons
C. Ions that are lighter in weight than electrons
D. Protons
Answer : B

24. The graph between an alternating quantity and time is called
A. Sine wave
B. Curve
C. Waveform
D. A plot
Answer : C

25. A gang capacitor is a variable capacitor in which capacitance is varied by changing the
A. Dielectric
B. Number of plates
C. Plate area
D. Distance between plates
Answer : C

26. Which one of the following elements serves as a protection against overload?
A. Fuse
B. Switch
C. Resistor
D. Relay
Answer : A

27. In a rectangular wavea the peak factor is
A.
B.
C.
D.
Answer : D

28. At what frequency will an inductor of 5mH have the same reactance as a capacitor of 0.1 F?
A. 7.12 kHz
B. 7.12 Hz
C. 7.12MHz
D. 7.12 GHz
Answer : A

29. For series capacitorsa total charge is
A. The sum of individual charges
B. Equal to the charge of either capacitors
C. Equal to the product of the charges
D. The quotient of the charges
Answer : B

30. When two in-phase sine waves that have identical frequency and amplitude are added togethera then the result is a sine wave with ___ the amplitude of either.
A. Half
B. Twice
C. Four times
D. One-fourth
Answer : B

31. The presence of an electric current is made known by
A. Electric shock
B. Effects produced
C. Magnetic shock
D. Flashing
Answer : B

32. Which of the following capacitors are used only in dc circuits?
A. Mica
B. Ceramic
C. Mylar
D. Electrolytic
Answer : D

33. When the net reactance in a series coil-capacitor circuit is zero at frequency fa the nature of its reactance of frequency 2f is
A. Inductive
B. Capacitive
C. Resistive
D. Infinite
Answer : A

34. Which component opposes voltage change?
A. Resistor
B. Inductor
C. Capacitor
D. Transistor
Answer : C

35. If a multiplate capacitor has 10 platesa each of area 10 cm2a then
A. 10 capacitors will be in parallel
B. 10 capacitors will be in series
C. 9 capacitors will be in parallel
D. 9 capacitors will be in series
Answer : C

36. Which of the following is a preferred resistor value?
A.
B.
C. 43a000
D. 54a321
Answer : B

37. 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

38. And ideal current source has an internal conductance of _____ siem
A. Infinite
B. One
C. Zero
D. One million
Answer : C

39. How many degrees of phase represents one full cycle?
A.
B.
C.
D.
Answer : A

40. The Q-factor of a parallel resonant circuit is also known as
A. Voltage magnification factor
B. Current magnification factor
C. Gain magnification factor
D. Resonance magnification factor
Answer : B

41. It is impossible to change the voltage across a capacitor instantlya as this would produce ___ current.
A. Infinite
B. Zero
C. Low
D. High
Answer : A

42. In a resonant circuita if Q ? 10 resonant frequency _______ bandwidth.
A. Bisects
B. Exceeds
C. Is less than
D. Is equal to
Answer : A

43. Resistor with colored bands in the body
A. Wire-wound resistor
B. Carbon-composition resistor
C. Potentiometer
D. Rheostat
Answer : B

44. Norton�s theorem is what form of an ac equivalent circuit?
A. Voltage
B. Current
C. Both voltage and current
D. Neither voltage nor current
Answer : B

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

46. Permeability is otherwise known as
A. Magnetic conductivity
B. Magnetic susceptibility
C. Electric conductivity
D. Electric susceptibility
Answer : A

47. An inductive load always has a ___ power factor
A. Leading
B. Lagging
C. Zero
D. Unity
Answer : B

48. 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

49. The ratio of the flux density to the electric field intensity in the dielectric is called
A. Permittivity
B. Field intensity
C. Permeability
D. Elasticity
Answer : A

50. A series RLCcircuit has a ______ power factor at its half-power points
A. Unity
B. Leading
C. Lagging
D. Either B or C
Answer : D