Engineering Reviewer - Electrical Circuits |

**Multiple Choice Questions / Practice Test**

**Electrical Circuits**

1. Conventional flow assumes charges flow from

A. Positive to negative

B. Positive to positive

C. Negative to positive

D. Negative to negative

2. Electron flow assumes charges flow from

A. Negative to positive

B. Negative to negative

C. Positive to negative

D. Positive to positive

3. Series resonance occurs when

A. XL = XC

B. XL = R

C. Z = R

D. Both A and C

4. The symbol Q refers to

A. Resonance quotient

B. Quality factor

C. Power quotient

D. Qualification test

5. The ratio of W/VA in an ac circuit means

A. Power factor

B. Reactive factor

C. Quality factor

D. Load factor

6. What is the reciprocal of quality factor?

A. Power factor

B. Reactive factor

C. Dissipation factor

D. 1/Q factor

7. In liquids and gases, 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

8. VL = VC in a series RLC circuit when

A. The value of the impedance is minimum

B. The power factor is zero

C. The current leads the total voltage by 90˚

D. The total voltage is zero

9. At what frequency will an inductor of 5mH have the same reactance as a capacitor of 0.1 μF?

A. 7.12 kHz

B. 7.12 Hz

C. 7.12MHz

D. 7.12 GHz

10. Property of an electric circuit that dissipates electric energy

A. Reactance

B. Impedance

C. Resistance

D. Conductance

11. What is the other name of relative permittivity?

A. Dielectric strength

B. Potential gradient

C. Breakdown voltage

D. Specific inductance capacity

12. In a series RLC circuit

A. The current lags VL by 90˚

B. The current leads VL by 90˚

C. XL leads XC by 90˚

D. Z = JXL at resonance

13. Resistor with colored bands in the body

A. Wire-wound resistor

B. Carbon-composition resistor

C. Potentiometer

D. Rheostat

14. In a resonant circuit, if Q ≥ 10 resonant frequency _______ bandwidth.

A. Bisects

B. Exceeds

C. Is less than

D. Is equal to

15. Which of the following conditions is not true for a series RLC circuit at resonance?

A. Z = JXL

B. XL = XC

C. The power factor is one

D. The magnitude of Z is √(R^2 + (XL-XC)^2)

16. The current is ____ times the maximum current at half-power points of a resonance curve.

A. 0.707

B. 1.414

C. 0.5

D. 0.632

17. 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

18. In an ac circuit with inductive reactance, the

A. Phase angle of the circuit is always 45˚

B. Voltage across the inductance must be 90˚ out-of-phase with the applied voltage

C. Current through the inductance lags its induced voltage by 90˚

D. Current through the inductance and voltage across it are180˚ out-of-phase

19. If three 9 mH inductors are connected in parallel without mutual inductance then the total inductance is

A. 3 mH

B. 9 mH

C. 27 mH

D. 18 mH

20. What is the specific resistance of a pure germanium?

A. 55 Ω-cm

B. 55 Ω-m

C. 55 Ω-mm

D. 55 kΩ-m

21. Two capacitors of capacitance 9 μF and 18 μF in series will have a total capacitance of

A. 27 μF

B. 162 μF

C. 6 μF

D. 180 μF

22. In a series RLC circuit

A. Increasing the frequency decreases the resistance

B. Increasing the frequency increases the resistance

C. Both XL and XC change as frequency changes

D. Impedance will always decrease

23. A series RLC circuit has a ______ power factor at its half-power points

A. Unity

B. Leading

C. Lagging

D. Either B or C

24. Kirchhoff’s laws (KCL and KVL) are applicable to

A. DC circuits

B. AC circuits

C. DC as well as AC circuits

D. Passive networks alone

25. A tank circuit is a

A. Parallel LC circuit

B. Series LC circuit

C. A resonant circuit

D. A non-resonant circuit

26. A capacitive load always has a ______ power facto

A. Leading

B. Lagging

C. Zero

D. Unity

27. What is the temperature coefficient of the resistance Eureka?

A. Infinity

B. Negative

C. Almost zero

D. Positive

28. As applied to a series RLC circuit, 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

29. 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

30. The open-circuit voltage at the terminal of load RL is 60V. Under the condition of maximum power transfer, the load voltage will be

A. 60 V

B. 15 V

C. 20 V

D. 30 V

31. If a capacitor is rated for 200V dc, what is its effective ac working voltage?

A. 50 V

B. 100 V

C. 200 V

D. 400 V

32. If resonant frequency is 10 kHz and quality factor is 50, then

A. Bandwidth is 200 Hz

B. XL = is 50,000 Ω

C. R is 50 Ω

D. XC = is 50,000 Ω

A. A series resonant circuit is of high impedance

B. A parallel resonant circuit is of low impedance

C. A series resonant circuit is inductive if it operates at a frequency higher than the resonant frequency

D. A parallel resonant circuit is inductive if it operates at a frequency higher than the resonant frequency

34. What is considered as the most important value of a sine wave?

A. Effective value

B. Peak value

C. Average value

D. Instantaneous value

35. An ac series circuit is composed of a resistance of 20 Ω, inductive reactance of 40 Ω, and a capacitive reactance of 15 Ω. If a current of 1 ampere is flowing, what is the applied voltage

A. 320 V

B. 32 V

C. 220 V

D. 22 V

36. 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

37. The value of temperature coefficient (α) 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

38. At what frequency will the current in a series RLC circuit reach its maximum value for an applied voltage of 15 V with R = 500 Ω, L = 100 μH and C = 0.001 μF?

A. 503 kHz

B. 403 kHz

C. 603 kHz

D. 303 kHz

39. If two equal resistances connected in series across a certain supply are now connected in parallel across the same supply, the power produced will be _____ that of series connection

A. One-half

B. One-fourth

C. Two times

D. Four times

40. The voltage lags the current by π/2 cycle in a

A. Purely resistive circuit

B. Purely inductive circuit

C. Purely capacitive circuit

D. Circuit containing resistance, capacitance and inductance

41. What is the half-power bandwidth of a parallel resonant circuit which has a resonant frequency of 3.6 MHz and Q of 218?

A. 1.65 kHz

B. 16.5 MHz

C. 16.5 kHz

D. 165 kHz

42. Which one of the following elements serves as a protection against overload?

A. Fuse

B. Switch

C. Resistor

D. Relay

43. Transient period is considered over after

A. 5 τ

B. 1 τ

C. 100 τ

D. 6 τ

44. What rating of a resistor determines its ability to absorb heat?

A. Wattage

B. Ohmic

C. Current

D. Voltage

45. 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

46. What is the reading of an ohmmeter for a shorted capacitor?

A. Zero

B. Infinity

C. k Ω

D. M Ω

47. What capacitance exists not through design but simply because two conducting surfaces are relatively close to each other?

A. Surge

B. Stray

C. Natural

D. Normal

48. The average value of a triangular or sawtooth wave is _____ times its peak value.

A. 0.577

B. 0.500

C. 0.318

D. 0.637

49. A series RLC circuit consists of a 10 Ω resistor in series with L = 10 μH, and C = 100 μF. Determine a new value of I, for which the resonant frequency is one –half the original value.

A. 40 μH

B. 40 mH

C. 40 pH

D. 40 nH

50. What is the peak factor of a triangular wave?

A. 1.16

B. 1.73

C. 1.41

D. 1.11

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