Welcome to your Alternating Current MCQs Mock Test of Class 12th Physics
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Q1. An ac circuit has a resistance of 12 ohm and an impedance of 15 ohm. The power factor of the circuit will be
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Q2. In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply. Which of the following elements are likely to constitute the circuit?
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Q.3. An AC voltage source of variable angular frequency ω and fixed amplitude V0 is connected in series with a capacitance C and an electric bulb of resistance R (inductance zero). When ω is increased then,
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Q.4. The dimensions of Inductance/Resistance is same as the dimension of
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Q.5. A bulb connected in series with a solenoid is lit by an AC source. If a soft iron core is introduced in the solenoid then,
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Q.6. In general in an alternating current circuit
7.
Q.7. The frequency of A.C. mains in India is
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Q.8. A.C. power is transmitted from a power house at a high voltage as
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Q.9. The electric mains supply in our homes and offices is a voltage that varies like a sine function with time such a voltage is called … A… and the current driven by it in a circuit is called the … B… Here, A and B refer to
10.
Q.10. Alternating currents can be produced by a
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Q.11. The peak value of the a.c. current flowing throw a resistor is given by
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Q.12. The alternating current can be measured with the help of
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Q.13. Alternating current can not be measured by D.C. ammeter, because
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Q.14. The heat produced in a given resistance in a given time by the sinusoidal current I0sinωt will be the same as that of a steady current of magnitude nearly
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Q.15. An A.C. source is connected to a resistive circuit. Which of the following is true?
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Q.16. A capacitor acts as an infinite resistance for
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Q.17. The capacitive reactance in an A.C. circuit is
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Q.18. Of the following about capacitive reactance which is correct?
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Q.19. Phase difference between voltage and current in a capacitor in an ac circuit is
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Q.20. A capacitor has capacitance C and reactance X, if capacitance and frequency become double, then reactance will be
21.
Q.21. When an ac voltage of 220 V is applied to the capacitor C, then
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Q.22. In LCR circuit if resistance increases quality factor
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Q.23. An inductor, a resistor and a capacitor are joined in series with an AC source. As the frequency of the source is slightly increased from a very low value, the reactance of the
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Q.24. With increase in frequency of an A.C. supply, the impedance of an L-C-R series circuit
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Q.25. If an LCR series circuit is connected to an ac source, then at resonance the voltage across
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Q.26. In an L.C.R. series a.c. circuit, the current
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Q.27. An LCR series circuit, connected to a source E, is at resonance. Then the voltage across
28.
Q.28. At resonance frequency the impedance in series LCR circuit is
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Q.29. At resonant frequency the current amplitude in series LCR circuit is
30.
Q.30. In tuning, we vary the capacitance of a capacitor in the tunning circuit such that the resonant frequency of the circuit becomes nearly equal to the frequency of the radio signal received. When this happens, the …A… with the frequency of the signal of the particular radio station in the circuit is maximum. Here A refers to
31.
Q.31. The power factor in a circuit connected to an A.C. The value of power factor is
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Q.32. Current in a circuit is wattless if
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Q.33. Power factor is one for
34.
Q.34. Power factor of the A. C. circuit varies between
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Q.35. The graph between inductive reactance and frequency is
36.
Q.36. For minimum dissipation of energy in the circuit the power factor should be
37.
Q.37. The opposition offered by ohmic and non ohmic components is
38.
Q.38. In which of the following circuits the maximum power dissipation is observed?
39.
Q.39. With increase in frequency of an A.C. supply, the inductive reactance
40.
Q.40. If the frequency of an A.C. is made 4 times of its initial value, the inductive reactance will
41.
Q.41. The transformer voltage induced in the secondary coil of a transformer is mainly due to
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Q.42. A transformer is employed to
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Q.43. Transformers are used
44.
Q.44. The loss of energy in the form of heat in the iron core of a transformer is
45.
Q.45. A transformer is based on the principle of
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Q.46. Quantity that remains unchanged in a transformer is
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Q.47. Eddy currents in the core of transformer can’t be developed by
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Q.48. The core of transformer is laminated to reduce
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Q.49. The transformation ratio in the step-up transformer is
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Q.50. Which of the following statements is/are correct ? I. In LCR series ac circuit, as the frequency of the source increases, the impedence of the circuit first decreases and then increases. II. If the net reactance of an LCR series ac circuit is same as its resistance, then the current lags behind the voltage by 45°. III. Below resonance, voltage leads the current while above it, current leads the voltage.
