Get ready for better learning with NCERT & CBSE Alternating Current Worksheet Class 12 Physics. No need to roam anywhere we will provide you with all the study content you need. Let’s study smartly. PDF view is also there for your suitability.
Electromagnetic Waves Worksheet
1. What is an alternating current ? Write an expression for its instantaneous value.
2. What is the frequency of direct current? [Himachal 99C]
3. Define the mean value of an alternating current. [Punjab 01]
4. Define the root mean square value of an alternating current.
5. What is the relation between peak value and the root mean square value of an alternating emf ? [Haryana 01]
6. The instantaneous current from an a.c. source is I = 5 sin 314t. What is the rms value of the current?
7. The instantaneous voltage from an a.c. source is given by ε = 300 sin 314t. What is the rms voltage of the source? [CBSE OD 2000]
8. The emf of an a.c. source is given by the expression: ε = 300 sin 314t
Write the values of peak voltage and frequency of the source.
9. What is peak value of voltage for 220 V a.c?
10. The divisions marked on the scale of an a.c. ammeter are not equally spaced. Why?
11. What is form-factor?
12. Define inductive reactance. Give its SI unit.
13. Define capacitive reactance. Give its SI unit. [CBSE D 15]
14. How does the capacitive reactance depend on frequency of a.c.?
15. How does inductive reactance depend on frequency of a.c. ?
16. What is the SI unit of 1/ ωC?
17. What is the reactance of a capacitor of capacitance C at f hertz? [ISCE 97]
18. What is the phase relationship between current and voltage in an inductor?
19. What is phase relationship between current and emf in an a.c. circuit containing a capacitor only ?
20. Sketch a graph showing the variation of inductive reactance with frequency of the applied voltage.
21. Sketch a graph showing the variation of the reactance of a capacitor with frequency of the applied voltage. [CBSE OD 01,15C]
22. What is the phase difference between the voltage across L and C in a series LCR-circuit connected to an a.c. source ? [CBSE D 98C]
23. Give the phase difference between the applied a.c. voltage and the current in an LCR circuit at resonance. [CBSE OD 97]
24. What is the capacitive reactance of a capacitor used in a circuit having d.c. emf ? Give reason. [Pb 92]
25. What is impedance?
26. When does a series LCR-circuit have minimum impedance?
27. A series LCR-circuit with L= 0.12 H, C = 4.8 × 10-7 F R = 23 Ω is connected to a variable frequency supply. At what frequency is the current maximum? [CBSE OD 90]
28. What is meant by admittance of an a.c. circuit?
29. Define power factor. [Haryana 01 ; Punjab 01]
30. What are the maximum and minimum values of power factor of a.c. circuit? [Punjab 99C]
Alternating Current Worksheet Class 12 Physics
31. For an ideal inductor, connected across a sinusoidal ac voltage source, state which one of the following quantity is zero : (i) Instantaneous power (ii) Average power over full cycle of the ac voltage source. [CBSE OD16C]
32. What is the power factor of an LCR series circuit at resonance?
33. What is wattless current ? [ISCE 2000 ; CBSE Dll]
34. A series LCR-circuit is connected to an a.c. source. In which of its part power dissipation occurs-L, C or R?
35. Define ‘quality factor’ of resonance in series LCR circuit. What is its SI unit? [CBSE D 16]
36. What is the significance of the Q-factor in an a.c. circuit? [CBSE D 17C]
37. Give the expression for power factor in an LR-circuit in terms of the resistance R and the inductive reactance XL. [ISCE 02]
38. In an a.c. circuit, R = 4 Ω, Z = 5 Ω, Vrms = 200 V and Kms = 1.5 A. Calculate the average power consumed over a full cycle. [ISCE 03]
39. What are the factors on which the power factor depends?
40. In a series LCR circuit, VL – VC ≠ VR. What is the value of power factor? [CBSE OD 15]
41. What is the function of a choke coil in a fluorescent tube?
42. How can we improve the Q-factor of a series resonant circuit?
43. What are (i) dimensions and (ii) units of product RC?
44. Is the direction of current during the discharging of capacitor same as that during the charging process?
45. What is the natural frequency of LC-circuit? What is the reactance of this circuit at this frequency?
46. What are the dimensions of √LC?
47. In a pure LC-circuit, what is the energy stored when the peak current is I0?
48. Where does the energy reside in a charged capacitor?
49. Where does the energy reside in an inductor when a current I0 is established in it?
50. State the principle of a.c. generator. [Haryana 95]
51. How can an a.c. generator be converted into d.c. generator? [Punjab 04]
52. State the principle of a transformer. [Haryana 97C]
53. An a.c. voltage of 200 V is applied to the primary of a transformer and voltage of 2000 V is obtained from the secondary coil. Calculate the ratio of currents in the primary and secondary coils. [CBSE Sample Paper 90]
54. Give two reasons for power loss in a transformer.
55. Which device will you use to step up a.c. voltage? Can we use the same device to set up d.c. voltage? [CBSE D 93C]
56. What is copper loss in a transformer? [Punjab 99]
57. What is iron loss in a transformer? [Punjab 2000]
58. How can iron loss in a transformer be reduced? [Punjab 98C, 99]
59. In a series LCR-circuit, the voltage across an inductor, capacitor and resistor are 20 V, 20 V and 40 V respectively. What is the phase difference between the applied voltage and the current in the circuit? [CBSE OD 05]
60. The power factor of an a.c. circuit is 0.5. What will be the phase difference between voltage and current in this circuit? [CBSE D 05 ; F 15]
61. Give expression for the average value of the a.c. voltage V = V0 sin ωt over the time interval t = 0 and t = π/ω [CBSE Sample Paper 08]
62. The instantaneous current and voltage of an ax. circuit are given by
i = 10 sin 314t A and v = 50 sin 314t V.
What is the power dissipation in the circuit? [CBSE OD 08]
63. The instantaneous current and voltage of an a.c. circuit are given by
What is the power dissipation in the circuit? [CBSE OD 08]
64. An electrical element X, when connected to an alternating voltage source, has the current through it leading the voltage by π / 2 radian. Identify X and write an expression for its reactance. [CBSE SP 08]
65. If the average power, supplied by an a.c. source, to a given circuit element, over a complete cycle, is found to be zero, what can be the possible nature of this element?
66. State the steady value of the reading of the ammeter in the circuit shown in Fig. 7.87.
67. State which of the two, the capacitor or an inductor, tends to become a SHORT when the frequency of the applied alternating voltage has a very high value. [CBSE SP 15]
68. Why is the use of a.c. voltage preferred over d.c. voltage? Give two reasons.