Electrical Circuits MCQ Solved Paper for NDA

1. A term used to express the amount of electrical energy stored in electrostatic field.
A. Joules
B. Coulombs
C. Watts
D. Electron-volt
Answer : A

2. At parallel resonancea the currents flowing through L and C are
A. Infinite
B. Zero
C. Unequal
D. Equal
Answer : D

3. In dividing or multiplying phasor quantitiesa ___ form is used.
A. Polar
B. Rectangular
C. Trigonometric
D. Exponential
Answer : A

4. 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

5. The open-circuit voltage at the terminal of load RL is 60V. Under the condition of maximum power transfera the load voltage will be
A. 60 V
B. 15 V
C. 20 V
D. 30 V
Answer : D

6. Which of the following does not refer to electrical energy?
A. Volt-ampere
B. Joule
C. Watt-second
D. Volt-coulomb
Answer : A

7. 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

8. 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

9. 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

10. What is expected when two 20 k a 1 watt resistor in parallel are use instead of one 10 k a 1 watt?
A. Provides higher current
B. Provides less power
C. Provides more power
D. Provides wider tolerance
Answer : C

11. What is the most common non-sinusoidal waveform?
A. Square wave
B. Triangular wave
C. Trapezoidal wave
D. Sawtooth wave
Answer : A

12. Which of the following does not generally affect the value of a capacitor?
A. The dielectric material used
B. The surface area of the plates
C. The thickness of the dielectric
D. The voltage applied to the plate
Answer : D

13. 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

14. Which of the following is a common material used in wire-wound resistors?
A. Manganin
B. Carbon
C. Bronze
D. German silver wire
Answer : A

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

16. Which of the statements below is not true?
A. Current source is an active element
B. Resistor is a linear element
C. Voltage source is a passive element
D. Diode is a non-linear element
Answer : C

17. The usual load of a dc circuit is a/an
A. Resistor
B. Capacitor
C. Inductor
D. Both inductor and capacitor
Answer : A

18. Which of the following represents the energy stored in a cap
A. CV2/2
B. 2Q2/C
C. C2/V
D. CV
Answer : A

19. The mutual inductance between two coils is ___ the reluctance of magnetic path.
A. Directly proportional to
B. Inversely proportional to
C. Independent to
D. Equal to
Answer : B

20. Which statement is true about a passive circuit?
A. A circuit with neither a source of current nor a source of potential difference
B. A circuit with a voltage source
C. A circuit with a current source
D. A circuit with only resistance as a load
Answer : A

21. A capacitor requires 12 C of charge to raise its potential of 3 V. What is the capacitance of the capacitor?
A. 36 F
B. 15 F
C. 0.25 F
D. 4 F
Answer : D

22. When two pure sine waves of the same frequency and the same amplitude which are exactly 180� outof-phase are added togethera the result is
A. A wave with twice the amplitude
B. A wave with half the amplitude
C. Zero signal
D. A wave with twice the frequency
Answer : C

23. 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

24. According to Gauss theorema flux can be equated to
A. Charge
B. Field intensity
C. Current
D. Voltage
Answer : A

25. Which of the following is not a factor affecting capacitance oor?
A. Area of plates
B. Number of plates
C. Distance between plates
D. Dielectric material used
Answer : B

26. A series RLCcircuit consists of a 10 resistor in series with L = 10 Ha and C= 100 F. Determine a new value of Ia for which the resonant frequency is one ±half the original value.
A. 40 H
B. 40 mH
C. 40 pH
D. 40 nH
Answer : A

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

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

29. The value of temperature coefficient ( ) is dependent upon
A. The nature of material and temperature
B. The length of material
C. The cross-sectional area of the material
D. The volume of the material
Answer : A

30. Which is considered as the effect of a dielectric material?
A. Increasing capacitance
B. Decreasing capacitance
C. Reducing the working voltage
D. Increasing the distance between the plates
Answer : A

31. In Norton�s theorema the short circuit current is obtained by
A. Opening the load terminals
B. Shorting the load terminals
C. Opening the voltage source
D. Shorting the voltage source
Answer : B

32. Another term of the quality factor of the resonant circuit.
A. Figure of merit
B. Figure of demerit
C. Noise factor
D. Noise figure
Answer : A

33. The temperature-resistance coefficient of pure gold is
A.
B.
C.
D.
Answer : A

34. If one resistance in a series connection is opena then
A. The current is zero in all the other resistances
B. The current is maximum in all the other resistances
C. The voltage is zero across the open resistance
D. The voltage is infinite across the open resistance
Answer : A

35. What fusion of elements is without chemical action between them?
A. Mixture
B. Compound
C. Alloy
D. Ionization
Answer : C

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

37. For maximum power transfera what is the relation between load resistance RL and internal resistance R of the voltage source?
A. RL= 2 r
B. RL= 1.5 r
C. RL= r
D. RL= 3 r
Answer : C

38. In a pure capacitancea
A. Current leads voltage by 90�
B. Current leads voltage by 180�
C. Current lags voltage by 90�
D. Current lags voltage by 180�
Answer : A

39. The maximum power transfer theorem is used in
A. Power system
B. Electronic system
C. Refrigeration
D. Air conditioning
Answer : B

40. The ___ of an alternating quantity is defined as the fractional part of a period or cycle through which the quantity has advanced from selected origin.
A. Phase
B. Frequency
C. Amplitude
D. Waveform
Answer : A

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

42. Effects of capacitance
A. It opposes any change in the amount of voltage
B. Voltage is lagged behind the current by a quarter cycle
C. Electric energy is stored in the capacitor in the form of electrostatic field
D. All of the above
Answer : D

43. 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

44. Two complex numbers or phasors are said to be conjugate if they
A. Differ only in the algebraic sign of their quadratic components
B. Differ only in the algebraic sign of their real components
C. Are equal in their real and quadrature components including alge
D. Are equal in their real components but differ in their quadrature components i ncluding algebraic signs.
Answer : A

45. A law which states that when a constant electromotive force is applied to a circuit consisting of a resistor and capacitor connected in seriesa the time taken for the potential on the plates of the capacitor to rise to any given fraction of its final value depends only on the product of capacitance and resistance.
A. Child�s law
B. CR law
C. Coulomb�s law
D. Debye T3 law
Answer : B

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

47. A trigger circuit consisting of a capacitor of 0.01 F is connected in series with a resistor. If the circuit requires 100 Vdcto operatea determine the value of the resistor when time constant is 0.009s.
A.
B. 900 k
C. 900 M
D. 900 G
Answer : B

48. 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

49. As applied to a series RLCcircuita bandwidth means
A. The frequency range for maximum power transfer
B. The difference between the highest and lowest frequencies of the oscillator
C. The separation of the half-power points
D. The frequency at which XL= XC
Answer : C

50. What is the conductance of a circuit having three 10 resistors in parallel?
A. 0.3 S
B. 3.33 S
C. 0.33 S
D. 30 S
Answer : A