Alternating Current Mock Test – Class 12 Physics

1. In a pure inductive circuit, the voltage phasor is drawn ahead of the current phasor. If current is taken as the reference phasor, the voltage phasor is drawn

2. Study the table and identify the row that describes an value suitably.

3. An ideal transformer steps down to . If the primary current is , the secondary current is

4. Two sinusoidal currents are represented by and . The two currents have the same

5. A pure capacitor is identified in a phasor diagram by the fact that

6. Assertion: A phasor can represent a sinusoidal quantity even though the actual current in a wire is not physically rotating in a circle.
Reason: The rotating phasor is a mathematical representation whose projection gives the sinusoidal instantaneous value.

7. In notation, is different from because refers to

8. A transformer supplies at on the secondary side. If it is ideal and the primary voltage is , the primary current is

9. Use the graph description below.

Compared with curve Q, curve P represents

10. At resonance, a series circuit with , , , and has voltage across the capacitor

11. The unit of impedance in a series circuit is

12. A claim says: “If and , the source must supply at least .” The claim is unsuitable because

13. A resonance curve for a series circuit plots on the vertical axis and frequency on the horizontal axis. The peak of the curve occurs at

14. Study the table and identify the suitable row for a pure inductive circuit.

15. A statement says: “At resonance in a series circuit, and are both zero.” The better correction is that

16. Study the table and identify the suitable row for a pure resistive circuit.

17. The resonant frequency of a series circuit is

18. When , a transformer is best described as a

19. In ideal transformer operation, . The relation between secondary and primary currents is

20. A pure inductor with is connected to a supply. Taking , its inductive reactance is approximately

21. A transformer core is laminated into thin insulated sheets. This construction mainly reduces heating caused by

22. For in a series circuit, the circuit behaves as

23. A lamp is to be operated from an supply with reduced current. Using a series resistor instead of a choke coil would waste more energy because the resistor

24. A label on an source gives and . From these labels alone, the two reported quantities are

25. Series resonance in an circuit occurs when

26. A phasor makes one complete rotation in . The frequency of the sinusoidal quantity represented by it is

27. If and in a pure resistor, the instantaneous power is

28. The average value of a sinusoidal alternating current over one complete cycle is zero mainly because

29. The statement for a sinusoidal voltage means that

30. A pure capacitor has and is connected to a source with . The rms current is

31. A choke coil is preferred over a resistor for limiting current mainly because an ideal choke coil

32. A choke coil used in an circuit should ideally have

33. A series circuit has , negligible inductive reactance, , and is connected to at . The average power is closest to

34. The source voltage magnitude in a series circuit can be written as

35. A resistor is connected to an supply of . The average power dissipated is

36. At resonance in a series circuit, the impedance is

37. A tuning circuit based on series resonance has and . Its bandwidth is

38. Use the graph description below.

The suitable conclusion is that

39. A sinusoidal current has . Its rms current is approximately

40. A voltage waveform reaches its positive maximum earlier than the current waveform in the same circuit. The voltage is then said to

41. At the frequency where in a series circuit, the phase angle between source voltage and current is

42. Taking , the resonant frequency of a series circuit with and is approximately

43. Use the energy description below.

The suitable energy identification is

44. Assertion: An ideal pure inductor has zero average power over a complete cycle.
Reason: In an ideal pure inductor, current lags voltage by .

45. A practical transformer differs from an ideal transformer because practical transformers have

46. In an ideal transformer, the voltage ratio is related to the turns ratio by

47. An ordinary transformer is connected to a steady source after the initial switching moment. The secondary emf is nearly zero because

48. Match the pure circuit features.

49. A series circuit has maximum current at resonance. At a half-power frequency, the current is closest to

50. For a sinusoidal alternating current with peak value , the rms value is