If two sinusoids of the same frequency but of different amplitudes and phase angles are subtracted, the resultant is

a sinusoid of the same frequency

a sinusoid of half the original frequency

a sinusoid of double the frequency

If two sine waves of the same frequency have a phase difference of JT radians, then

when one wave reaches its maxi¬mum value, the other will reach its minimum value

both will reach their minimum values at the same instant

both will reach their maximum values at the same instant

when one wave reaches its maxi¬mum value, the other will reach its minimum value

The phase difference between voltage and current wave through a circuit element is given as 30°. The essential condition is that

both waves must have same frequency

both waves must have identical peak values

both waves must have zero value at the same time

Capacitive reactance is more when

capacitance is less and frequency of supply is less

capacitance is less and frequency of supply is more

capacitance is more and frequency of supply is less

capacitance is more and frequency of supply is more

Power factor of an electrical circuit is equal to

cosine of phase angle difference be-tween current and voltage

ratio of useful current to total cur¬rent Iw/I

The best place to install a capacitor is

across the terminals of the inductive load

far away from the inductive load

reduces load handling capability of electrical system

results in more power losses in the electrical system

overloads alternators, transformers and distribution lines

results in more voltage drop in the line

Pure inductive circuit

takes power from the line during some part of the cycle and then returns back to it during other part of the cycle

does not take power at all from a line

takes power from the line during some part of the cycle and then returns back to it during other part of the cycle

Inductance affects the direct current flow

at the time of turning on and off

only at the time of turning off

at the time of turning on and off

Inductance of a coil Varies

directly as the cross-sectional area of magnetic core

directly as square of number of turns

directly as the permeability of the core

inversely as the length of the iron path

Time constant of an inductive circuit

increases with increase of inductance and decrease of resistance

increases with the increase of inductance and the increase of resistance

increases with the decrease of inductance and decrease of resistance

increases with decrease of inductance and increase of resistance

In a highly capacitive circuit the

reactive power is more than the actual power

apparent power is equal to the actual power

reactive power is more than the apparent power

reactive power is more than the actual power

actual power is more than its reactive power

Power factor of the system is kept high

to maximise the utilization of the capacities of generators, lines and transformers

to reduce voltage regulation of the line

The time constant of the capacitance circuit is defined as the time during which voltage

rises to 63.2% of its final steady value

falls to 36.8% of its final steady value

rises to 38.6% of its final steady value

rises to 63.2% of its final steady value

The r.m.s. value of alternating current is given by steady (D.C.) current which when flowing through a given circuit for a given time produces

the same heat as produced by A.C. when flowing through the same circuit

the more heat than produced by A.C. when flowing through the same circuit

the same heat as produced by A.C. when flowing through the same circuit

the less heat than produced by A.C. flowing through the same circuit

The square waveform of current has following relation between r.m.s. value and average value.

r.m.s. value is equal to average value

r.m.s. value of current is greater than average value

r.m.s. value of current is less than average value

The transient currents are associated with the

changes in the stored energy in the inductors and capacitors

In the case of an unsymmetrical alternating current the average value must always be taken over

unsymmetrical part of the wave form

In a pure resistive circuit

current is in phase with the voltage

current lags behind the voltage by 90°

current leads the voltage by 90°

current can lead or lag the voltage by 90°

current is in phase with the voltage

In a pure inductive circuit

the current lags behind the voltage by 90°

the current is in phase with the voltage

the current lags behind the voltage by 90°

the current leads the voltage by 90°

the current can lead or lag by 90°

increases with the increase in supply frequency

is unaffected by the supply frequency

decreases with the increase in supply frequency

increases with the increase in supply frequency

becomes zero with the increase in supply frequency

In any A.C. circuit always

apparent power is more than actual power

reactive power is more than apparent power

actual power is more than reactive power

reactive power is more than actual power

Pure inductive circuit takes power from the A.C. line when

applied voltage decreases but current increases

applied voltage increases but current decreases

both applied voltage and current increase

both applied voltage and current decrease

AC Fundamentals Circuits and Circuit Theory MCQ Questions and Answers PDF Quiz

55.

In a R-L-C circuit

power is consumed in resistance and is equal to I R

exchange of power takes place between inductor and supply line

exchange of power takes place between capacitor and supply line

exchange of power does not take place between resistance and the supply line

all above are correct

1. A sine wave has a frequency of 50 Hz. Its angular frequency is _______ radian/second.

2. The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance becomes_____ohms.

3. The period of a sine wave is _____ seconds. Its frequency is

4. A heater is rated as 230 V, 10 kW, A.C. The value 230 V refers to

5. If two sinusoids of the same frequency but of different amplitudes and phase angles are subtracted, the resultant is

6. The peak value of a sine wave is 200 V. Its average value is

7. If two sine waves of the same frequency have a phase difference of JT radians, then

8. The voltage of domestic supply is 220V. This figure represents

9. Two waves of the same frequency have opposite phase when the phase angle between them is

10. The power consumed in a circuit element will be least when the phase difference between the current and oltage is

11. For the same peak value which of the following wave will ‘have the highest r.m.s. value ?

12. For the same peak value, which of the following wave has the least mean value ?

13. For a sine wave with peak value Imax the r.m.s. value is

14. Form Factor is the ratio of

15. Form factor for a sine wave is

16. For a sine wave with peak value Emax______8.30. the average value is

17. For a frequency of 200 Hz, the time period will be

18. The phase difference between voltage and current wave through a circuit element is given as 30°. The essential condition is that

19. The r.m.s. value of a sinusoidal A.C. current is equal to its value at an angle of______degrees.

20. Capacitive reactance is more when

21. In a series resonant circuit, the impedance of the circuit is

22. Power factor of an electrical circuit is equal to

23. The best place to install a capacitor is

24. Poor power factor

25. Capacitors for power factor correction are rated in

26. Pure inductive circuit

27. Inductance affects the direct current flow

28. Inductance of a coil Varies

29. All the rules and laws of D.C. circuit also apply to A.C. circuit containing

30. Time constant of an inductive circuit

31. Power factor of an inductive circuit is usually improved by connecting capacitor to it in

32. In a highly capacitive circuit the

33. Power factor of the following circuit will be zero

34. Power factor of the following circuit will be unity

35. Power factor of the system is kept high

36. The time constant of the capacitance circuit is defined as the time during which voltage

37. In a loss-free R-L-C circuit the transient current is

38. The r.m.s. value of alternating current is given by steady (D.C.) current which when flowing through a given circuit for a given time produces

39. The square waveform of current has following relation between r.m.s. value and average value.

40. The double energy transient occur in the

41. The transient currents are associated with the

42. The power factor at resonance in R-L- C parallel circuit is

43. In the case of an unsymmetrical alternating current the average value must always be taken over

44. In a pure resistive circuit

45. In a pure inductive circuit

46. In a circuit containing R, L and C, power loss can take place in

47. Inductance of coil

48. In any A.C. circuit always

49. In a purely inductive circuit

50. Power factor of electric bulb is

51. Pure inductive circuit takes power from the A.C. line when

52. Time constant of a circuit is the time in seconds taken after the application of voltage to each

53. Time constant of a capacitive circuit

54. Magnitude of current at resonance in R-L-C circuit

55. In a R-L-C circuit

56. In R-L-C series resonant circuit magnitude of resonance frequency can be changed by changing the value of

57. In a series L-C circuit at the resonant frequency the

58. The time constant of a series R-C circuit is given by

59. If resistance is 20 Q. and inductance is 27 in a R-L series circuit, then time constant of this circuit will be

60. Which of the following coil will have large resonant frequency ?

61. If a sinusoidal wave has frequency of 50 Hz with 30 A r.m.s. current which of the following equation represents this wave ?

Time

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1.

A sine wave has a frequency of 50 Hz. Its angular frequency is _______ radian/second.

2.

The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance becomes_____ohms.

3.

The period of a sine wave is _____ seconds. Its frequency is

4.

A heater is rated as 230 V, 10 kW, A.C. The value 230 V refers to

5.

If two sinusoids of the same frequency but of different amplitudes and phase angles are subtracted, the resultant is

6.

The peak value of a sine wave is 200 V. Its average value is

7.

If two sine waves of the same frequency have a phase difference of JT radians, then

8.

The voltage of domestic supply is 220V. This figure represents

9.

Two waves of the same frequency have opposite phase when the phase angle between them is

10.

The power consumed in a circuit element will be least when the phase difference between the current and oltage is

11.

For the same peak value which of the following wave will ‘have the highest r.m.s. value ?

12.

For the same peak value, which of the following wave has the least mean value ?

13.

For a sine wave with peak value Imax the r.m.s. value is

14.

Form Factor is the ratio of

15.

Form factor for a sine wave is

16.

For a sine wave with peak value Emax______8.30. the average value is

17.

For a frequency of 200 Hz, the time period will be

18.

The phase difference between voltage and current wave through a circuit element is given as 30°. The essential condition is that

19.

The r.m.s. value of a sinusoidal A.C. current is equal to its value at an angle of______degrees.

20.

Capacitive reactance is more when

21.

In a series resonant circuit, the impedance of the circuit is

22.

Power factor of an electrical circuit is equal to

23.

The best place to install a capacitor is

24.

Poor power factor

25.

Capacitors for power factor correction are rated in

26.

Pure inductive circuit

27.

Inductance affects the direct current flow

28.

Inductance of a coil Varies

29.

All the rules and laws of D.C. circuit also apply to A.C. circuit containing

30.

Time constant of an inductive circuit

31.

Power factor of an inductive circuit is usually improved by connecting capacitor to it in

32.

In a highly capacitive circuit the

33.

Power factor of the following circuit will be zero

34.

Power factor of the following circuit will be unity

35.

Power factor of the system is kept high

36.

The time constant of the capacitance circuit is defined as the time during which voltage

37.

In a loss-free R-L-C circuit the transient current is

38.

The r.m.s. value of alternating current is given by steady (D.C.) current which when flowing through a given circuit for a given time produces

39.

The square waveform of current has following relation between r.m.s. value and average value.

40.

The double energy transient occur in the

41.

The transient currents are associated with the

42.

The power factor at resonance in R-L- C parallel circuit is

43.

In the case of an unsymmetrical alternating current the average value must always be taken over

44.

In a pure resistive circuit

45.

In a pure inductive circuit

46.

In a circuit containing R, L and C, power loss can take place in

47.

Inductance of coil

48.

In any A.C. circuit always

49.

In a purely inductive circuit

50.

Power factor of electric bulb is

51.

Pure inductive circuit takes power from the A.C. line when

52.

Time constant of a circuit is the time in seconds taken after the application of voltage to each

53.

Time constant of a capacitive circuit

54.

Magnitude of current at resonance in R-L-C circuit

55.

In a R-L-C circuit

56.

In R-L-C series resonant circuit magnitude of resonance frequency can be changed by changing the value of

57.

In a series L-C circuit at the resonant frequency the

58.

The time constant of a series R-C circuit is given by

59.

If resistance is 20 Q. and inductance is 27 in a R-L series circuit, then time constant of this circuit will be

60.

Which of the following coil will have large resonant frequency ?

61.

If a sinusoidal wave has frequency of 50 Hz with 30 A r.m.s. current which of the following equation represents this wave ?