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Alternating Current

62 questions · Physics · NEET
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Alternating Current

62 questions · Physics · NEET

  1. To an ac power supply of 220 V at 50 Hz , a resistor of 20Ω, a capacitor of reactance 25Ω and an inductor of reactance 45Ω are connected in series. The corresponding current in the circuit and the phase angle…2025 · Q156 · MCQ
  2. In an ideal transformer, the turns ratio is NS​NP​​=21​. The ratio VS​:VP​ is equal to (the symbols carry their usual meaning) :2024 · Q159 · MCQ
  3. A 10μF capacitor is connected to a 210 V,50 Hz source as shown in figure. The peak current in the circuit is nearly (π=3.14) : Includes diagram2024 · Q196 · MCQ
  4. In the circuit shown below, the inductance L is connected to an ac source. The current flowing in the circuit is I=I0​sinωt. The voltage drop (VL​) across L is Includes diagram2024 · Q160 · MCQ
  5. A step up transformer is connected to an ac mains supply of 220 V to operate at 11000 V,88 watt. The current in the secondary circuit, ignoring the power loss in the transformer, is2024 · Q164 · MCQ
  6. The amplitude of the charge oscillating in a circuit decreases exponentially as Q=Q0​e−Rt/2L, where Q0​ is the charge at t=0 s. The time at which charge amplitude decreases to 0.50Q0​ is nearly: [Given that R=1.5Ω,L=12 mH,ln(2)=0.693…2024 · Q199 · MCQ
  7. An ac source is connected in the given circuit. The value of ϕ will be : Includes diagram2023 · Q137 · MCQ
  8. If Z1​ and Z2​ are the impedances of the given circuits (a) and (b) as shown in figures, then choose the correct option Includes diagram2023 · Q152 · MCQ
  9. The maximum power is dissipated for an ac in a/an:2023 · Q155 · MCQ
  10. For very high frequencies, the effective impedance of the circuit (shown in the figure) will be:- Includes diagram2023 · Q168 · MCQ
  11. In a series LCR circuit, the inductance L is 10 mH, capacitance C is 1 μF and resistance R is 100 Ω. The frequency at which resonance occurs is :-2023 · Q124 · MCQ
  12. A 12 V,60 W lamp is connected to the secondary of a step down transformer, whose primary is connected to ac mains of 220 V. Assuming the transformer to be ideal, what is the current in the primary…2023 · Q138 · MCQ
  13. An ac source is connected to a capacitor C. Due to decrease in its operating frequency2023 · Q144 · MCQ
  14. The magnetic energy stored in an inductor of inductance 4 μH carrying a current of 2 A is :2023 · Q151 · MCQ
  15. The net impedance of circuit (as shown in figure) will be : Includes diagram2023 · Q172 · MCQ
  16. Given below are two statements Statement I : In an a.c circuit, the current through a capacitor leads the voltage across it. Statement II : In a.c circuit containing pure capacitance only, the phase difference between the current and…2022 · Q150 · MCQ
  17. An inductor of inductance 2 mH is connected to a 220 V, 50 Hz ac source. Let the inductive reactance in the circuit is X1. If a 220 V dc source replace the ac source in the circuit, then the inductive reactance in the circuit is X2. X1 and…2022 · Q157 · MCQ
  18. A standard filament lamp consumes 100 W when connected to 200 V ac mains supply. The peak current through the bulb will be :2022 · Q169 · MCQ
  19. The peak voltage of the ac source is equal to2022 · Q145 · MCQ
  20. A series LCR circuit with inductance 10 H, capacitance 10 μF, resistance 50 Ω is connected to an ac source of voltage, V = 200sin(100t) volt. If the resonant frequency of the LCR circuit is v0 and the frequency of the ac source…2022 · Q165 · MCQ
  21. An inductor of inductance L, a capacitor of capacitance C and a resistor of resistance 'R' are connected in series to an ac source of potential difference 'V' volts as shown in figure. Potential difference across L, C and R is 40V, 10V and… Includes diagram2021 · Q128 · MCQ
  22. A capacitor of capacitance 'C', is connected across an ac source of voltage V, given by V = V0sinωt The displacement current between the plates of the capacitor, would then be given by :2021 · Q135 · MCQ
  23. A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit ?2021 · Q164 · MCQ
  24. A series LCR circuit containing 5.0 H inductor, 80μF capacitor and 40Ω resistor is connected to 230V variable frequency ac source. The angular frequencies of the source at which power transferred to the circuit is half the power…2021 · Q167 · MCQ
  25. A 40 μF capacitor is connected to a 200 V. 50 Hz ac supply. The rms value of the current on the circuit is, nearly :2020 · Q155 · MCQ
  26. A series LCR circuit is connected to an ac voltage source. When L is removed from the circuit, the phase difference between current and voltage is 3π​. If instead C is removed from the circuit, the phase difference is again 3π​…2020 · Q160 · MCQ
  27. The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance2018 · Q124 · MCQ
  28. An inductor 20 mH, a capacitor 100 μF and a resistor 50 Ω are connected in series across a source of emf, V = 10 sin 314 t. The power loss in the circuit is2018 · Q126 · MCQ
  29. Figure shows a circuit that contains three identical resistors with resistance R = 9.0 Ω each, two identical inductors with inductance L = 2.0 mH each, and an ideal battery with emf ε=18V. The current i through… Includes diagram2017 · Q132 · MCQ
  30. A small signal voltage V(t) = V0 sinωt is applied across an ideal capacitor C2016 · Q125 · MCQ
  31. An inductor 20 mH, a capacitor 50 μF and a resistor 40 Ω are connected in series across a source of emf V = 10 sin 340t. The power loss in A.C. circuit is2016 · Q127 · MCQ
  32. Which of the following combinations should be selected for better tuning of an L-C-R circuit used for combination ?2016 · Q126 · MCQ
  33. The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. The power factor of this circuit is2016 · Q128 · MCQ
  34. A 100 Ω resistance and a capacitor of 100 Ω reactance are connected in series across a 220 V source. When the capacitor is 50% charged, the peak value of the displacement current is2016 · Q129 · MCQ
  35. A series R-C circuit is connected to an alternating voltage source. Consider two situations : (a) When capacitor is air filled. (b) When capacitor is mica filled. Current through resistor is I and voltage across capacitor is V then2015 · Q118 · MCQ
  36. A resistance 'R' draws power 'P' when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes 'Z'. the power drawn will be2015 · Q123 · MCQ
  37. A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6 A, the voltage across the secondary coil and the current in the primary coil respectively are2014 · Q128 · MCQ
  38. The primary of a transformer when connected to a dc battery of 10 Volt draws a current of 1 mA. The number of turns of the primary and secondary windings are 50 and 100 respectively. The voltage in the secondary and the current drawn by…2013 · Q130 · MCQ
  39. A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when2013 · Q130 · MCQ
  40. The instantaneous values of alternating current and voltage in a circuit are given as i=2​1​ sin (100 πt) ampere e=2​1​sin(100πt+3π​) Volt The average power…2012 · Q90 · MCQ
  41. The current (I) in the inductance is varying with time according to the plot shown in figure. Which one of the following is the correct variation of voltage with time in the coil ? Includes diagram2012 · Q137 · MCQ
  42. In an electrical circuit R, L, C and a.c. voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and the current in the circuit is If instead, C is removed from the circuit,…2012 · Q138 · MCQ
  43. A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz frequency. If an ac source, of 200 volt, 100 Hz, is connected across the coil, the current in the coil will be2011 · Q90 · MCQ
  44. The r.m.s. value of potential difference V shown in the figure is Includes diagram2011 · Q91 · MCQ
  45. An ac voltage is applied to a resistance R and an inductor L in series. If R and the inductive reactance are both equal to 3 Ω, the phase difference between the applied voltage and the current in the circuit is2011 · Q127 · MCQ
  46. In the ac circuit an alternating voltage e = 2002​sin100t volts is connected to a capacitor of capacity 1 μF. The r.m.s. value of the current in the circuit is2011 · Q128 · MCQ
  47. A condenser of capacity C is charged to a potential difference of V1. The plates of th condenser are then connected to an ideal inductor of inductance L. The current through the inductor when the potential difference across the condenser…2010 · Q83 · MCQ
  48. In the given circuit the reading of voltmeter V1 and V2 are 300 volts each. The reading of the voltmeter V3 and ammeter A are respectively Includes diagram2010 · Q148 · MCQ
  49. A 220 volt input is supplied to a transformer. The output circuit draws a current of 2.0 ampere at 440 volts. If the efficiency of the transformer is 80%, the current drwn by the primary windings of the transformer is2010 · Q149 · MCQ
  50. Power dissipated in an LCR series circuit connected to an A.C. source of emf ε is2009 · Q141 · MCQ
  51. In an a.c. circuit the e.m.f. (ε) and the current (i) at any instant are given respectively by ε = E0sinωt, i = I0sin(ωt − ϕ) The average power in the circuit over one cycle of a.c. is2008 · Q133 · MCQ
  52. A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 amp, the efficiency of the transformer is approximately2007 · Q116 · MCQ
  53. What is the value of inductance L for which the current is maximum in a series LCR circuit with C = 10 μF and ω = 1000 s−1 ?2007 · Q117 · MCQ
  54. The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux ϕ linked with the primary coil is given by ϕ = ϕ0 + 4t, where ϕ is webers, t is time in seconds and ϕ0…2007 · Q118 · MCQ
  55. A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produce oscillations of frequency f. If L is doubled and C is changed to 4C, the frequency will be2006 · Q129 · MCQ
  56. A coil of inductive reactance 31 Ω has a resistance of 8 Ω. It is placed in series with a condenser of capacitative reactance 25 Ω. The combination is connected to an a.c. source of 110 V. The power factor of the…2006 · Q139 · MCQ
  57. The core of a transformer is laminated because2006 · Q140 · MCQ
  58. In a circuit L, C and R are connected in series with an alternating voltage source of frquency f. The current leads the voltage by 45o. The value of C is2005 · Q136 · MCQ
  59. A coil of 40 henry inductance is connected in series with a resistance of 8 ohm and the combination is joined to the terminals of a 2 volt battery. The time constant of the circuit is2004 · Q127 · MCQ
  60. For a series LCR circuit the power loss at resonance is2002 · Q136 · MCQ
  61. A capacitor of capacity C has reactance X. If capacitance and frequency become double then reactance will be2001 · Q133 · MCQ
  62. The value of quality factor is2001 · Q134 · Multiple correct