**Short Questions**

1. A circuit an iron – cored inductor a switch and a D.C source arranged in series.The switch is closed and after an interval reopened.Explain why a spark jumps across the switch contacts?

2. A sinusoidal current has rms value of 10 A.What is the maximum or peak value?

3. An inductor draws 30 ampers when connected across the terminals of generator A and 6 ampers when connected to B.Assuming the same impressed voltage can you tell which of the two generators A or B is an A.C machine?Give reasons for your answer?

4. Can electrolysis proceed with the help of an A.C source ?

5. Define alternating current (A.C) ?

6. Define direct current (D.C) ?

7. Define impedance and write its unit ?

8. Define impedence of a circuit and give its unit?

9. Define inductive reactance ?

10. Define peak value of voltage or current ?

11. Define power ?

12. Define power factor in A.C?

13. Define root mean square value (i.e. r.m.s) ?

14. Define Root Mean square value of A.C. Voltage?

15. Define time period of an alternating voltage ?

16. Describe some advantages of 3- phase A.C.supply?

17. Describe some important properties of a series resonant circuit?

18. Describe some important properties of parallel resonant circuit?

19. Describe the condition under which the reactance of a capacitor will be small ?

20. Describe the condition which will make the reactance small?

21. Describe the principle upon which the electromagnetic waves can be generated?

22. Describe the types of modulation?

23. Differentiate between Peak value and Peak to Peak value?

24. Explain the conditions under which electromagnetic waves are produced from source?

25. Explain the term peak to peak value ?

26. How an A.C flows through a capacitor ?

27. How are the radio waves received?

28. How current and voltage behave in a R-L series circuit ?

29. How current and voltage behave in an inductive circuit ?

30. How does doubling the frequency affect the reactance of (a) an inductance (b) a capacitor?

31. How many time per second will an inductance lamp reach maximum brilliance when connected to a 50Hz source?

32. How series circuit ?

33. How the out put voltage of an alternating current generator varies with time ?

34. How the radio waves are received ?

35. How the receptian of a particular radio station is selected on your radio set?

36. If ‘T’ is the time period of an A.C then find the frequency of an A.C ?

37. In a R- L circuit will the current lag or lead the voltage?IIIustrate your answer by a vector diagram?

38. Name a device that will (a) permit the flow of direct current but not the alternating current (b) permit alternatig current but not the direct current?

39. Name the device that will (a) permit flow of direct current but oppose the flow of alternating current.(b) permit flow of alternating current but not the direct current?

40. Name the type of modulation ?

41. Show that resonance at the resonance frequency is given as fr= 1/2πLC?

42. What are conditions for representing A.C voltage or current by vector diagram?

43. What are electromagnetic waves ?

44. What are metal detectors ?

45. What are the basic controlling elements of an A.C circuit ?

46. What are the frequencies range for an amplitude modulation transmission ?

47. What are the frequencies range for frequency modulation transmission ?

48. What are the magnitude of Vᵣₘₛ and Iᵣₘₛ respectively ?

49. What do you mean by instantaneous value ?

50. What do you mean by phase of an A.C ?

51. What do you understand about three phases A.C supply?

52. What do you understand by electromagnetic waves?

53. What do you understand by inductive reactance?

54. What do you understand by modulation and modulated carrier wave?

55. What is a choke?

56. What is a choke?Why it is used in A.C circuits?

57. What is a modulation signal ?

58. What is a power factor in an A.C circuit ?

59. What is a R-C series circuit ?

60. What is a resonance circuit ?

61. What is a R-L series circuit ?

62. What is an inductor ?

63. What is choke ?

64. What is impedance?Write its unit?

65. What is meant by A.M and F. M?

66. What is meant by electrical inertia ?

67. What is meant by frequency modulation (F.M.) ?

68. What is meant by impedence?Explain briefly.

69. What is modulation ?

70. What is peak value?

71. What is reactance of a capacitor ?

72. What is reactance?

73. What is resonance frequency of a R-L-C series circuit ?

74. What is the circuit impedance at the resonance frequency ?

75. What is the condition of resonance in a parallel resonance circuit?

76. What is the most common source of alternating voltage ?

77. What is the phase on the A.C wave form at the negative peak ?

78. What is the phase on the A.C waveform at the positive peak ?

79. What is the power through a resistor when both the current and voltage are in phase ?

80. What is the quantity of charge stored on the plates of a capacitor at any istant ?

81. What is the shape of graph for alternating voltage and time ?

82. What is the source of transmitting electromagnetic waves?

83. What is the speed of electromagnetic waves in free space ?

84. What is the type of a circuit used in metal détector ?

85. What is the use of inductor coil ?

86. What the net potential difference alternating voltage of an R-L-C series circuit ?

87. When electromagnetic discovered ?

88. Whether electromagnetic waves require a medium for transmission ?

89. Which apparatus electromagnetic waves ?

90. Why D.C can not flow through a capacitor ?

91. Write some important properties of a series resonance circuit ?

92. Write some important properties of parallel resonant circuit ?

93. Write the equation of impedance of a R-L series circuit ?

**Long Questions**

1. Define alternating current. Also explain time period and waveform of alternating current.

2. What is the root mean square value of alternating current?

3. Define phase of A.C. Define phase lag and phase head.

4. Describe A.C. through a capacitor.

5. Describe A.C. through an inductor.

6. Explain R.L series circuit.

7. Explain series resonance circuit also discuss its properties.

8. What is parallel resonance circuit? Describe its properties. Also find the resonance frequency for the circuit.

9. Describe the principle of metal detectors.

10. What are the electromagnetic waves?

“11. Explain the principle of generation, transmission and reception of electromagnetic waves with an example. “

12. Explain modulation with its types.

13. An alternating current is represented by the equation I = 20 sin 100 πt. Compute frequency and the maximum and r.m.s values of current.

14. A sinusoidal A.C. has a maximum value of 15 A. What are its r.m.s. values? If the time is recorded from the instant the current is zero and is becoming positive, what is the instantaneous value of the current after 1/300 s, given the frequency is 50 Hz.

15. Find the value of current and inductive reactance when A.C voltage of 220 V at 50 Hz is passed through an inductor of 10 H.

16. A circuit has an inductance of 1/π H and resistance of 2000 ohm. A 50 Hz A.C. is supplied to it. Calculate the reactance and impedance offered by the circuit.

17. An inductor of pure inductance 3/π H is connected in series with a resistance of 40 ohm. Find (i) the peak value of the current (ii) the r.m.s value, and (iii) the phase difference between the current and the applied voltage V = 350 sin (100 π t).

18. A 10mH, 20 ohm coil is connected across 240 V and 180/π Hz source. How much power does it dissipate?

19. Find the value of the current flowing through a capacitance 0.5 micro F when connected to a source of 150 V at 50 Hz.

20. An alternating source e.m.f 12 V and frequency 50 Hz is applied to a capacitor of capacitance 3 micro F in series with a resistor of resistance 1 ohm. Calculate the phase angle.

21. What is the resonant frequency of a circuit which included a coil of inductance 2.5 H and a capacitance 40 micro F?

22. An inductor of inductance 150 micro F is parallel with a variable capacitor whose capacitance can be changed from 500 pico F to 20 pico F. Calculate the maximum frequency and minimum frequency for which the circuit can be tuned.