Physics · JEE Main, NEET

Alternating Current

190 practice questions with a worked solution for each. Tap an option to see instantly if you are right.

139MCQ51Numerical45With diagram
Start with question 1 See it move: AC circuits, phasors and resonance
  1. 1In a series LCR circuit with L=10 mHL = 10\,\text{mH}, C=1 μFC = 1\,\mu\text{F}, the resonant angular frequency ω0\omega_0 is:JEE Main/MCQ/Medium
  2. 2In an AC circuit, voltage V=100sin⁡(100t)V = 100\sin(100t) and current I=100sin⁡(100t+π/3)I = 100\sin(100t + \pi/3). Power factor is:NEET/MCQ/Medium
  3. 3In a series LCR circuit, R=10 Ω,L=100 mH,C=10 μFR=10\,\Omega, L=100\,\text{mH}, C=10\,\mu\text{F}. Quality factor QQ of the circuit is:JEE Main/MCQ/Medium
  4. 4The electric current in the circuit is given as i=io(t/T)i=i_{\mathrm{o}}(t / T). The r.m.s current for the period t=0t=0 to t=Tt=T is ____\_\_\_\_.JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  5. 5An inductor of reactance 100Ω100 \Omega, a capacitor of reactance 50Ω50 \Omega, and a resistor of resistance 50Ω50 \Omega are connected in series with an AC source of 10 V , 50 Hz. Average power dissipated by the circuit is ________ W.JEE Main/Numerical/Medium/Alternating Current, Voltage and Power
  6. 6An ac current is represented as
    i=52+10cos⁡(650πt+π6)Amp\mathrm{i}=5 \sqrt{2}+10 \cos \left(650 \pi \mathrm{t}+\frac{\pi}{6}\right) \mathrm{Amp}
    The r.m.s value of the current is    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  7. 7An alternating current is represented by the equation, i=1002sin⁡(100πt)i=100 \sqrt{2} \sin (100 \pi t) ampere. The RMS value of current and the frequency of the given alternating current areJEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  8. 8An electric bulb rated as 100 W−220 V100 \mathrm{~W}-220 \mathrm{~V} is connected to an ac source of rms voltage 220 V. The peak value of current through the bulb is :JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  9. 9Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
    Assertion (A) : Choke coil is simply a coil having a large inductance but a small resistance. Choke coils are used with fluorescent mercury-tube fittings. If household electric power is directly connected to a mercury tube, the tube will be damaged.
    Reason (R): By using the choke coil, the voltage across the tube is reduced by a factor \(\left(R / \sqrt{R^2+\omega^2 L^2}\right)\), where \(\omega\) is frequency of the supply across resistor \(R\) and inductor L . If the choke coil were not used, the voltage across the resistor would be the same as the applied voltage.
    In the light of the above statements, choose the most appropriate answer from the options given below :    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  10. 10An alternating current is given by I=IAsin⁡ωt+IBcos⁡ωt\mathrm{I}=\mathrm{I}_{\mathrm{A}} \sin \omega \mathrm{t}+\mathrm{I}_{\mathrm{B}} \cos \omega \mathrm{t}. The r.m.s current will beJEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  11. 11A alternating current at any instant is given by i=[6+56sin⁡(100πt+π/3)]i=[6+\sqrt{56} \sin (100 \pi t+\pi / 3)] A. The rmsr m s value of the current is ________ A.JEE Main/Numerical/Medium/Alternating Current, Voltage and Power
  12. 12In an ac circuit, the instantaneous current is zero, when the instantaneous voltage is maximum. In this case, the source may be connected to :
    A. pure inductor.
    B. pure capacitor.
    C. pure resistor.
    D. combination of an inductor and capacitor.
    Choose the correct answer from the options given below :    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  13. 13A parallel plate capacitor has a capacitance C=200pFC=200pF. It is connected to 230V230V ac supply with an angular frequency 300rads−1300rad{s}^{-1}. The rms value of conduction current in the circuit and displacement current in the capacitor respectively are :JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  14. 14An AC voltage V=20sin⁡200πtV=20\sin 200\pi t is applied to a series LCR circuit which drives a current I=10sin⁡(200πt+π3)I=10\sin \left(200\pi t+\dfrac{\pi }{3}\right). The average power dissipated is:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  15. 15An alternating voltage V(t)=220sin⁡100πtV(t)=220\sin 100\pi t volt is applied to a purely resistive load of 50Ω50\Omega. The time taken for the current to rise from half of the peak value to the peak value is:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  16. 16In an a.c. circuit, voltage and current are given by: V=100sin⁡(100t)VV=100\sin (100t)V and I=100sin⁡(100t+π3)mAI=100\sin \left(100t+\dfrac{\pi }{3}\right)mA respectively. The average power dissipated in one cycle is :JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  17. 17A capacitor of capacitance 150.0μF150.0\mu F is connected to an alternating source of emf given by E=36sin⁡(120πt)VE=36\sin \left(120\pi t\right)V. The maximum value of current in the circuit is approximately equal to:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  18. 18A series LCR circuit consists of R=80ΩR=80Ω. XL=100Ω{X}_{L}=100Ω, and XC=40Ω{X}_{C}=40Ω. The input voltage is 2500cos⁡(100πt)V2500\cos \left(100\pi t\right)V. The amplitude of current, in the circuit, is _____ AA.JEE Main/Numerical/Medium/Alternating Current, Voltage and Power
  19. 19An alternating voltage source V=260sin⁡(628t)V=260\sin (628t) is connected across a pure inductor of 5mH5mH. Inductive reactance in the circuit is:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  20. 20An alternating emf E=440sin⁡100πtE=440\sin 100\pi t is applied to a circuit containing an inductance of 2πH\dfrac{\sqrt{2}}{\pi }H. If an a.c. ammeter is connected in the circuit, its reading will be :JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  21. 21The equation of current in a purely inductive circuit is 5sin⁡(49πt−30∘)5\sin \left(49\pi t-30^{\circ}\right). If the inductance is 30mH30mH then the equation for the voltage across the inductor, will beJEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  22. 22A direct current of 4A4A and an alternating current of peak value 4A4A flow through resistance of 3Ω3\Omega and 2Ω2\Omega respectively. The ratio of heat produced in the two resistances in same interval of time will be :JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  23. 23An inductor of 0.5mH0.5mH, a capacitor of 200μF200\mu F and a resistor of 2Ω2\Omega are connected in series with a 220V220V ac source. If the current is in phase with the emf, the frequency of ac source will be ______×102Hz\times {10}^{2}Hz.JEE Main/Numerical/Medium/Alternating Current, Voltage and Power
  24. 24A telegraph line of length 100km100km has a capacity of 0.01μFkm−10.01\mu F{km}^{-1} and it carries an alternating current at 0.50.5 kilo cycle per second. If minimum impedance is required, then the value of the inductance that needs to be introduced in series is _____ mHmH. (If π=10\pi =\sqrt{10})JEE Main/Numerical/Medium/Alternating Current, Voltage and Power
  25. 25The current flowing through an ac circuit is given by I=5sin⁡(120πt)AI=5\sin \left(120\pi t\right)A. How long will the current take to reach the peak value starting from zero?JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  26. 26A sinusoidal voltage V(t)=210sin⁡3000tV\left(t\right)=210\sin 3000t volt is applied to a series LCR circuit in which L=10mH,C=25μFL=10mH,C=25\mu F and R=100ΩR=100\Omega. The phase difference (Φ)\left(\Phi \right) between the applied voltage and resultant current will beJEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  27. 27Given below are two statements :
    Statement-I: The reactance of an ac circuit is zero. It is possible that the circuit contains a capacitor and an inductor.
    Statement-II: In ac circuit, the average power delivered by the source never becomes zero.
    In the light of the above statements, choose the correct answer from the options given below    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  28. 28As shown in the figure an inductor of inductance 200mH200mH is connected to an ACAC source of emf 220V220Vand frequency 50Hz50Hz. The instantaneous voltage of the source is 0V0V when the peak value of current is aπA\dfrac{\sqrt{a}}{\pi }A. The value of aa is _____ .
    JEE Main/Numerical/Medium/Alternating Current, Voltage and Power/With diagram
  29. 29A resistance of 40Ω40\Omega is connected to a source of alternating current rated 220V,50Hz220V,50Hz. Find the time taken by the current to change from its maximum value to the rms value :JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  30. 30At very high frequencies, the effective impedance of the given circuit will be _________Ω.\Omega .
    JEE Main/Numerical/Medium/Alternating Current, Voltage and Power/With diagram
  31. 31An AC circuit has an inductor and a resistor of resistance RR in series, such that XL=3R{X}_{L}=3R. Now, a capacitor is added in series such that XC=2R{X}_{C}=2R. the ratio of the new power factor with the old power factor of the circuit is 5:x\sqrt{5}:x. The value of xx isJEE Main/Numerical/Medium/Alternating Current, Voltage and Power
  32. 32The alternating current is given by, i={42sin⁡(2πTt)+10}Ai=\left\{\sqrt{42}\sin \left(\dfrac{2\pi }{T}t\right)+10\right\}A. The R.M.S. value of this current is __________ AA.JEE Main/Numerical/Medium/Alternating Current, Voltage and Power
  33. 33In the given circuit the ACAC source has ω=100rads−1\omega =100rad{s}^{-1}. Considering the inductor and capacitor to be ideal, what will be the current II flowing through the circuit?
    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power/With diagram
  34. 34A 10Ω10\Omega resistance is connected across 220V−50Hz220V-50Hz AC supply. The time taken by the current to change from its maximum value to the rmsrms value is:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  35. 35In a circuit consisting of a capacitance and a generator with alternating emf, Eg=Egosinωt,VC{E}_{g}={E}_{go}sin\omega t,{V}_{C} and IC{I}_{C} are the voltage and current. Correct phasor diagram for such circuit is
    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power/With diagram
  36. 36ACAC voltage V(t)=20sin⁡ωtV(t)=20\sin \omega t of frequency 50Hz50Hz is applied to a parallel plate capacitor. The separation between the plates is 2mm2mm and the area is 1m21{m}^{2}. The amplitude of the oscillating displacement current for the applied ACAC voltage is [Takeϵ0=8.85×10−12Fm−1]\left[\text{Take}{\epsilon }_{0}=8.85\times {10}^{-12}F{m}^{-1}\right]JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  37. 37An ACAC source rated 220V,50Hz220V,50Hz is connected to a resistor. The time taken by the current to change from its maximum to the rms value is :JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  38. 38What happens to the inductive reactance and the current in a purely inductive circuit if the frequency is halved ?JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  39. 39Match List-I with List-II List-i List-II a Phase difference between current and voltage in a purely resistive AC circuit i π2;\dfrac{\pi }{2}; current leads
    voltage b Phase difference between current and
    voltage in a pure inductive AC circuit ii zero c Phase difference between current and
    voltage in a pure capacitive AC circuit iii     π2;\dfrac{\pi }{2}; current lags
    voltage d Phase difference between current and
    voltage in an LCR series circuit iv     tan⁡−1(XC−XLR){\tan }^{-1}\left(\dfrac{{X}_{C}-{X}_{L}}{R}\right) Choose the most appropriate answer from the options given below :    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  40. 40An ACAC current is given by I=I1sinωt+I2cosωt.I={I}_{1}sin\omega t+{I}_{2}cos\omega t.
    A hot wire ammeter will give a reading:    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  41. 41Find the peak current and resonant frequency of the following circuit (as shown in figure).
    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power/With diagram
  42. 42An alternating current is given by the equation i=i1sin⁡ωt+i2cos⁡ωti={i}_{1}\sin \omega t+{i}_{2}\cos \omega t. The rms current will be:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  43. 43Match List I with List II. List I List II (a) Rectifier (i) Used either for stepping up or stepping down the A.C. voltage (b) Stabilizer (ii) Used to convert A.C. voltage into D.C. voltage (c) Transformer (iii) Used to remove any ripple in the rectified output voltage (d) Filter (iv) Used for constant output voltage even when the input voltage or load current change Choose the correct answer from the options given below:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  44. 44A part of a complete circuit is shown in the figure. At some instant, the value of current I is 1A1A and it is decreasing at a rate of 102As−1{10}^{2}{As}^{-1}. The value of the potential difference Vp−VQ,{V}_{p}-{V}_{Q}, (in volts) at that instant is-
    JEE Main/Numerical/Medium/Alternating Current, Voltage and Power/With diagram
  45. 45An alternating voltage V(t)=220sin⁡(100πt)V(t)=220\sin \left(100\pi t\right) volt is applied to a purely resistive load of 50Ω50\Omega . The time taken for the current to rise from half of the peak value to the peak value is:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  46. 46

    In the above circuit,     C=32μF,R2=20Ω,L=310HC=\dfrac{\sqrt{3}}{2}\mu F, {R}_{2}=20\Omega , L=\dfrac{\sqrt{3}}{10}H and R1=10Ω.{R}_{1}=10\Omega . Current in L-R1L\text{-}{R}_{1} path is I1{I}_{1} and in C−R2C-{R}_{2} path it is I2.{I}_{2}. The voltage of ACsourceisgivenby,V=2002 sin(100 t)AC source is given by, V=200 2  sin( 100 t ) volts. The phase difference between I1{I}_{1} and I2{I}_{2} is:    JEE Main/MCQ/Medium/Alternating Current, Voltage and Power/With diagram
  47. 47A series ACAC circuit containing an inductor (20mH),\left(20 mH\right), a capacitor (120μF)\left(120\text{μ}F\right) and a resistor (60Ω)\left(60 \Omega \right) is driven by an ACAC source of 24V/50Hz.24 V/50 Hz. The energy dissipated in the circuit in 60s60 s is:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  48. 48The AC voltage across a resistance can be measured using a:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  49. 49A sinusoidal voltage V(t)=100sin⁡(500t)\mathrm{V}(\mathrm{t})=100 \sin (500 \mathrm{t}) is applied across a pure inductance of L=0.02HL=0.02 \mathrm{H}. The current through the coil is:JEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  50. 50In an a.c. circuit the voltage applied is E=E0sin⁡ωt\mathrm{E}=\mathrm{E}_0 \sin \omega \mathrm{t}. The resulting current in the circuit is I=I0sin⁡(ωt−π2)\mathrm{I}=\mathrm{I}_0 \sin \left(\omega \mathrm{t}-\frac{\pi}{2}\right). The power consumption in the circuit is given byJEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  51. 51A metal wire of linear mass density of 9.8 g/m9.8 \mathrm{~g} / \mathrm{m} is stretched with a tension of 10 kg10 \mathrm{~kg}-wt between two rigid supports 1 metre apart. The wire passes at its middle point between the poles of a permanent magnet, and it vibrates in resonance when carrying an alternating current of frequency nn. The frequency nn of the alternating source isJEE Main/MCQ/Medium/Alternating Current, Voltage and Power
  52. 52A LCR series circuit driven with Erms=90E_{rms} = 90 V at frequency fd=30f_d = 30 Hz has resistance R=80 ΩR = 80\,\Omega, an inductance with inductive reactance XL=20.0 ΩX_L = 20.0\,\Omega and capacitance with capacitive reactance XC=80.0 ΩX_C = 80.0\,\Omega. The power factor of the circuit is _______.JEE Main/MCQ/Medium/AC Circuits
  53. 53A series LCR circuit with R=20 ΩR = 20\ \Omega, L=1.6 HL = 1.6\text{ H} and C=40 μFC = 40\ \mu\text{F} is connected to a variable frequency a.c. source. The inductive reactance at resonant frequency is _______ Ω\Omega.JEE Main/Numerical/Medium/AC Circuits
  54. 54An a.c. source of angular frequency ω\omega is connected across a resistor RR and a capacitor CC in series. The current is observed as II. Now the frequency of the source is changed to ω/4\omega/4, (keeping the voltage unchanged) the current is found to be I/3I/3. The ratio of resistance to reactance at frequency ω\omega isJEE Main/MCQ/Medium/AC Circuits
  55. 55An inductor of 1010 mH, capacitor of 0.1 μ0.1\ \muF and a resistor of 100 Ω100\ \Omega are connected in series across an a.ca.c power supply 220220 V, 7070 Hz. The power factor of the given circuit is 0.50.5. The difference in the inductive reactance and capacitance reactance is 3α Ω\sqrt{3}\alpha\ \Omega. The value of α\alpha is _____.JEE Main/Numerical/Medium/AC Circuits
  56. 56The figure given below shows an LCRLCR series circuit with two switches S1S_1 and S2S_2. When switch S1S_1 is closed keeping S2S_2 open, the phase difference (ϕ)(\phi) between the current and source voltage is 30°30° and phase difference is 60°60° when S2S_2 is closed keeping S1S_1 open. The value of (3L1−L2)(3L_1 - L_2) is _______ H.
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  57. 57An inductor stores 16 J of magnetic field energy and dissipates 32 W of thermal energy due to its resistance when an a.c. current of 2 A (rms) and frequency 50 Hz flows through it. The ratio of inductive reactance to its resistance is ____\_\_\_\_. (π=3.14)(\pi=3.14)JEE Main/Numerical/Medium/AC Circuits
  58. 58Using a variable frequency a.c. voltage source the maximum current measured in the given LCR circuit is 50 mA for V=5sin⁡(100t)V=5 \sin (100 t) The values of LL and RR are shown in the figure. The capacitance of the capacitor (C) used is ____\_\_\_\_ μF\mu \mathrm{F}.
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  59. 59A capacitor CC is first charged fully with potential difference of V0V_{0} and disconnected from the battery. The charged capacitor is connected across an inductor having inductance LL. In t s 25%t \mathrm{~s} \ 25 \% of the initial energy in the capacitor is transferred to the inductor. The value of tt is ____\_\_\_\_ s.JEE Main/MCQ/Medium/AC Circuits
  60. 60For ac circuit shown in figure, R=100kΩ\mathrm{R}=100 \mathrm{k} \Omega and C=100pF\mathrm{C}=100 \mathrm{pF} and the phase difference between Vin \mathrm{V}_{\text {in }} and (VB−VA)\left(V_B-V_A\right) is 90∘90^{\circ}. The input signal frequency is 10xrad/sec10^x \mathrm{rad} / \mathrm{sec}, where ' x ' is ______
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  61. 61In a series LCR circuit, a resistor of 300Ω300 \Omega, a capacitor of 25 nF and an inductor of 100 mH are used. For maximum current in the circuit, the angular frequency of the ac source is _____ ×104\times 10^4 radians s−1\mathrm{s}^{-1}.JEE Main/Numerical/Medium/AC Circuits
  62. 62A series LCR circuit is connected to an alternating source of emf E. The current amplitude at resonant frequency is I0I_0. If the value of resistance R becomes twice of its initial value then amplitude of current at resonance will beJEE Main/MCQ/Medium/AC Circuits
  63. 63A capacitor of reactance 43Ω4 \sqrt{3} \Omega and a resistor of resistance 4Ω4 \Omega are connected in series with an ac source of peak value 82 V8 \sqrt{2} \mathrm{~V}. The power dissipation in the circuit is ________ W.JEE Main/Numerical/Medium/AC Circuits
  64. 64An alternating emf E=1102sin⁡100t\mathrm{E}=110 \sqrt{2} \sin 100 \mathrm{t} volt is applied to a capacitor of 2μF2 \mu \mathrm{F}, the rms value of current in the circuit is _____mA\mathrm{mA},JEE Main/Numerical/Medium/AC Circuits
  65. 65A coil of negligible resistance is connected in series with 90Ω90 \Omega resistor across 120 V,60 Hz120 \mathrm{~V}, 60 \mathrm{~Hz} supply. A voltmeter reads 36 V36 \mathrm{~V} across resistance. Inductance of the coil is :JEE Main/MCQ/Medium/AC Circuits
  66. 66A LCR circuit is at resonance for a capacitor CC, inductance LL and resistance RR. Now the value of resistance is halved keeping all other parameters same. The current amplitude at resonance will be now:JEE Main/MCQ/Medium/AC Circuits
  67. 67For a given series LCR circuit it is found that maximum current is drawn when value of variable capacitance is 25nF25 \mathrm{nF}. If resistance of 200Ω200 \Omega and 100mH100 \mathrm{mH} inductor is being used in the given circuit. The frequency of ac source is ______ ×103 Hz\times 10^3 \mathrm{~Hz}. (given π2=10\pi^2=10 )JEE Main/Numerical/Medium/AC Circuits
  68. 68When a dcd c voltage of 100 V100 \mathrm{~V} is applied to an inductor, a dcd c current of 5 A5 \mathrm{~A} flows through it. When an ac voltage of 200 V200 \mathrm{~V} peak value is connected to inductor, its inductive reactance is found to be 203Ω20 \sqrt{3} \Omega. The power dissipated in the circuit is _______ W.JEE Main/Numerical/Medium/AC Circuits
  69. 69Given below are two statements:
    Statement I: In an LCR series circuit, current is maximum at resonance.
    Statement II: Current in a purely resistive circuit can never be less than that in a series LCR circuit when connected to same voltage source.
    In the light of the above statements, choose the correct from the options given below:    JEE Main/MCQ/Medium/AC Circuits
  70. 70A series LCR circuit is subjected to an ac signal of 200 V,50 Hz200 \mathrm{~V}, 50 \mathrm{~Hz}. If the voltage across the inductor (L=10mH)(\mathrm{L}=10 \mathrm{mH}) is 31.4 V31.4 \mathrm{~V}, then the current in this circuit is _____ .JEE Main/MCQ/Medium/AC Circuits
  71. 71An ac source is connected in given series LCR circuit. The rms potential difference across the capacitor of 20μF20 \mu \mathrm{F} is _____V.
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  72. 72Match List I with List II

     Choose the correct answer from the options given below: \text { Choose the correct answer from the options given below: }    JEE Main/MCQ/Medium/AC Circuits/With diagram
  73. 73In series LCR circuit, the capacitance is changed from CC to 4C4C. To keep the resonance frequency unchanged, the new inductance should be :JEE Main/MCQ/Medium/AC Circuits
  74. 74In the given figure, the charge stored in 6μF6\mu F capacitor, when points AA and BB are joined by a connecting wire is _______μC\mu C.
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  75. 75Given below are two statements:
    Statement I : An AC circuit undergoes electrical resonance if it contains either a capacitor or an inductor.
    Statement II: An AC circuit containing a pure capacitor or a pure inductor consumes high power due to its non-zero power factor. In the light of above statements, choose the correct answer from the options given below:    JEE Main/MCQ/Medium/AC Circuits
  76. 76Given below are two statements:
    Statement I : When the frequency of an AC source in a series LCR circuit increases, the current in the circuit first increases, attains a maximum value and then decreases.
    Statement II : In a series LCR circuit, the value of power factor at resonance is one.
    In the light of given statements, choose the most appropriate answer from the options given below.    JEE Main/MCQ/Medium/AC Circuits
  77. 77
    As per the given graph, choose the correct representation for curve     AA and curve BB
    {Where     XC={X}_{C}= Reactance of pure capacitive circuit connected with A.C. source
    XL={X}_{L}= Reactance of pure inductive circuit connected with A.C. source
    R=R= Impedance of pure resistive circuit connected with A.C. source
    Z=Z= Impedance of the LCRLCR series circuit }    JEE Main/MCQ/Medium/AC Circuits/With diagram
  78. 78Given below are two statements:
    Statement I: Maximum power is dissipated in a circuit containing an inductor, a capacitor and a resistor connected in series with an     ACAC source, when resonance occurs.
    Statement II: Maximum power is dissipated in a circuit containing pure resistor due to zero phase difference between current and voltage.
    In the light of the above statements, choose the correct answer from the options given below:    JEE Main/MCQ/Medium/AC Circuits
  79. 79An oscillating LCLCcircuit consists of a 75mH75mH inductor and a 1.2µF1.2µF capacitor. If the maximum charge to the capacitor is 2.7µC2.7µC. The maximum current in the circuit will be _______mA.JEE Main/Numerical/Medium/AC Circuits
  80. 80A series LCR circuit is connected to an ac source of 220V,50Hz220V,50Hz. The circuit contain a resistance R=100ΩR=100\Omega and an inductor of inductive reactance XL=79.6Ω{X}_{L}=79.6\Omega. The capacitance of the capacitor needed to maximize the average rate at which energy is supplied will be ______ μF\mu F.JEE Main/Numerical/Medium/AC Circuits
  81. 81An inductor of 0.5mH0.5mH, a capacitor of 20μF20\mu F and resistance of 20Ω20\Omega are connected in series with a 220V220V ac source. If the current is in phase with the emf, the amplitude of current of the circuit is xA\sqrt{x}A. The value of xx is-JEE Main/Numerical/Medium/AC Circuits
  82. 82In the given circuit, rmsrms value of current (Irms)\left({I}_{rms}\right) through the resistor RR is :
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  83. 83An inductor of inductance 2μH2\mu H is connected in series with a resistance, a variable capacitor and an AC source of frequency 7kHz7kHz. The value of capacitance for which maximum current is drawn into the circuit is 1xF\dfrac{1}{x}F, where the value of xx is ______.
    (Take     π=227\pi =\dfrac{22}{7})    JEE Main/Numerical/Medium/AC Circuits
  84. 84For the given figures, choose the correct options:
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  85. 85An LCR series circuit of capacitance 62.5nF62.5nF and resistance of 50Ω50\Omega, is connected to an A.C. source of frequency 2.0kHz2.0kHz. For maximum value of amplitude of current in circuit, the value of inductance is ____mHmH.(Takeπ2=10)\left.(\text{Take}{\pi }^{2}=10\right)JEE Main/Numerical/Medium/AC Circuits
  86. 86In an LC oscillator, if values of inductance and capacitance become twice and eight times, respectively, then the resonant frequency of oscillator becomes xx times its initial resonant frequency ω0{\omega }_{0}. The value of xx is:JEE Main/MCQ/Medium/AC Circuits
  87. 87A capacitor of capacitance 500μF500\mu F is charged completely using a de supply of 100V100V. It is now connected to an inductor of inductance 50mH50mH to form an LC circuit. The maximum current in LC circuit will be _____ AA.JEE Main/Numerical/Medium/AC Circuits
  88. 88A circuit element XX when connected to an AC supply of peak voltage 100V100V gives a peak current of 5A5A which is in phase with the voltage. A second element YY when connected to the same AC supply also gives the same value of peak current which lags behind the voltage by π2\dfrac{\pi }{2}. If XX and YY are connected in series to the same supply, what will be the rms value of the current in ampere?JEE Main/MCQ/Medium/AC Circuits
  89. 89A coil of inductance 1H1H and resistance 100Ω100\Omega is connected to a battery of 6V6V. Determine approximately :
    (a) The time elapsed before the current acquires half of its steady-state value
    (b) The energy stored in the magnetic field associated with the coil at an instant     15ms15ms after the circuit is switched on. (Given ln⁡2=0.693\ln 2=0.693, e−32=0.25{e}^{\dfrac{-3}{2}}=0.25)    JEE Main/MCQ/Medium/AC Circuits
  90. 90The frequencies at which the current amplitude in an LCR series circuit becomes 12\dfrac{1}{\sqrt{2}} times its maximum value, are 212rads−1212rad{s}^{-1} and 232rads−1232rad{s}^{-1}. The value of resistance in the circuit is R=5ΩR=5\Omega. The self inductance in the circuit is _____ mHmH.JEE Main/Numerical/Medium/AC Circuits
  91. 91A series LCR circuit has L=0.01H,R=10ΩL=0.01H,R=10\Omega and C=1μFC=1\mu F and it is connected to ac voltage of amplitude (Vm)50V\left({V}_{m}\right)50V. At frequency 6060% lower than resonant frequency, the amplitude of current will be approximatelyJEE Main/MCQ/Medium/AC Circuits
  92. 92To light, a 50W,100V50W,100V lamp is connected, in series with a capacitor of capacitance 50πxμF\dfrac{50}{\pi \sqrt{x}}\mu F, with 200V,50HzAC200V,50HzAC source. The value of xx will be _____ .JEE Main/Numerical/Medium/AC Circuits
  93. 93The effective current II in the given circuit at very high frequencies will be _____ AA.
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  94. 94When you walk through a metal detector carrying a metal object in your pocket, it raises an alarm. This phenomenon works onJEE Main/MCQ/Medium/AC Circuits
  95. 95The RMS value of conduction current in a parallel plate capacitor is 6.9μA6.9\mu A. The capacity of this capacitor, if it is connected to 230V230V AC supply with an angular frequency of 600rads−1600rad{s}^{-1}, will beJEE Main/MCQ/Medium/AC Circuits
  96. 96To increase the resonant frequency in series LCR circuit,JEE Main/MCQ/Medium/AC Circuits
  97. 97For a series LCRLCR circuit, II vs ω\omega curve is shown

    (a) To the left of     ωr{\omega }_{r}, the circuit is mainly capacitive.
    (b) To the left of     ωr{\omega }_{r}, the circuit is mainly inductive.
    (c) At     ωr{\omega }_{r}, impedance of the circuit is equal to the resistance of the circuit.
    (d) At     ωr{\omega }_{r}, impedance of the circuit is 00.
    Choose the most appropriate answer from the options given below.    JEE Main/MCQ/Medium/AC Circuits/With diagram
  98. 98In the given circuit, the magnitude of VL{V}_{L} and VC{V}_{C} are twice that of VR{V}_{R}. Given that f=50Hzf=50Hz, the inductance of the coil is 1KπmH\dfrac{1}{K\pi }mH. The value of KK is _____ .
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  99. 99An AC source is connected to an inductance of 100mH100mH, a capacitance of 100μF100\mu F and a resistance of 120Ω120\Omega as shown in figure. The time in which the resistance having a thermal capacity 2JC−1∘2JC-1^{\circ} will get heated by 16∘C16^{\circ}C is _____ ss.
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  100. 100A 110V,50Hz,AC110V,50Hz,AC source is connected in the circuit (as shown in figure). The current through the resistance 55Ω55\Omega, at resonance in the circuit, will be _____AA.
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  101. 101In a series LCR circuit, the inductance, capacitance and resistance are L=100mHL=100mH, C=100μFC=100\mu Fand R=10ΩR=10\Omega respectively. They are connected to an ACAC source of voltage 220V220V and frequency of 50Hz50Hz. The approximate value of current in the circuit will be _____ AA.
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  102. 102If wattless current flows in the ACAC circuit, then the circuit is :JEE Main/MCQ/Medium/AC Circuits
  103. 103In an ac circuit, an inductor, a capacitor and a resistor are connected in series with XL=R=XC.{X}_{L}=R={X}_{C}. Impedance of this circuit is :JEE Main/MCQ/Medium/AC Circuits
  104. 104An inductor coil stores 64J64J of magnetic field energy and dissipates energy at the rate of 640W640W when a current of 8A8A is passed through it. If this coil is joined across an ideal battery, find the time constant of the circuit (in ss).JEE Main/MCQ/Medium/AC Circuits
  105. 105A series LCR circuit driven by 300V300V at a frequency of 50Hz50Hz contains a resistance R=3kΩR=3k\Omega, an inductor of inductive reactance XL=250πΩ{X}_{L}=250\pi \Omega and an unknown capacitor. The value of capacitance to maximise the average power should be:
    (takeπ2=10)\left(\text{take}{\pi }^{2}=10\right)    JEE Main/MCQ/Medium/AC Circuits
  106. 106A 100Ω100\Omega resistance, a 0.1μF0.1\mu F capacitor and an inductor are connected in series across a 250V250V supply at variable frequency. Calculate the value of inductance of inductor at which resonance will occur. Given that the resonant frequency is 60Hz60Hz.JEE Main/MCQ/Medium/AC Circuits
  107. 107A 0.07H0.07H inductor and a 12Ω12\Omega resistor are connected in series to a 220V,50Hz220V,50Hz AC source. The approximate current in the circuit and the phase angle between current and source voltage are respectively.
    [Take     π\pi as 227]\left.\dfrac{22}{7}\right]    JEE Main/MCQ/Medium/AC Circuits
  108. 108Two circuits are shown in figure (a)(a) and (b)(b). At a frequency of _______ rads−1rad{s}^{-1} the average power dissipated in one cycle will be the same in both the circuits.
    JEE Main/Numerical/Medium/AC Circuits/With diagram
  109. 109An inductor of 10mH10mH is connected to a 20V20V battery through a resistor of 10kΩ10k\Omega and a switch. After a long time, when maximum current is set up in the circuit, the current is switched off. The current in the circuit after 1μs1\mu s is x100mA\dfrac{x}{100}mA. Then xx is equal to ______ . (Take e−1=0.37{e}^{-1}=0.37)JEE Main/Numerical/Medium/AC Circuits
  110. 110Match List-I with List-II. List - I List - II (a) ωL>1ωC\omega L\gt \dfrac{1}{\omega C} (i) Current is in phase with emf (b) ωL=1ωC\omega L=\dfrac{1}{\omega C} (ii) Current lags behind the applied emf (c) ωL<1ωC\omega L\lt \dfrac{1}{\omega C} (iii) Maximum current occurs (d) Resonant frequency (iv) Current leads the emf Choose the correct answer from the options given below.JEE Main/MCQ/Medium/AC Circuits
  111. 111A series LCR circuit of R=5Ω,L=20mHR=5\Omega ,L=20mH and C=0.5μFC=0.5\mu F is connected across an ACAC supply of 250V,250V, having variable frequency. The power dissipated at resonance condition is ________×102W.\times {10}^{2}W.JEE Main/Numerical/Medium/AC Circuits
  112. 112For a series LCRLCR circuit with R=100Ω,L=0.5mHR=100\Omega ,L=0.5mH and C=0.1pFC=0.1pF connected across 220V−50Hz220V-50Hz ACAC supply, the phase angle between
    current and supplied voltage and the nature of the circuit is:    JEE Main/MCQ/Medium/AC Circuits
  113. 113In an LCRLCR series circuit, an inductor 30mH30mH and a resistor 1Ω1\Omega are connected to an ACAC source of angular frequency 300rads−1.300rad{s}^{-1}. The value of capacitance for which the current leads the voltage by 45∘45^{\circ} is 1x×10−3F\dfrac{1}{x}\times {10}^{-3}F. Then the value of xx isJEE Main/Numerical/Medium/AC Circuits
  114. 114The time taken for the magnetic energy to reach 2525% of its maximum value, when a solenoid of resistance RR, inductance LL is connected to a battery, is :JEE Main/MCQ/Medium/AC Circuits
  115. 115In a scries LCRLCR resonance circuit, if we change the resistance only, from a lower to higher value :JEE Main/MCQ/Medium/AC Circuits
  116. 116A sinusoidal voltage of peak value 250V250V is applied to a series LCRLCR circuit, in which R=8Ω,L=24mHR=8\Omega ,L=24mH and C=60μFC=60\mu F. The value of power dissipated at resonant condition is xx kWkW. The value of xx to the nearest integer is _______.JEE Main/Numerical/Medium/AC Circuits
  117. 117An RCRC circuit as shown in the figure is driven by a ACAC source generating a square wave. The output wave pattern monitored by CROCRO would look close to :
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  118. 118In a series LCR resonant circuit, the quality factor is measured as 100100. If the inductance is increased by two fold and resistance is decreased by two fold, then the quality factor after this change will be _______JEE Main/Numerical/Medium/AC Circuits
  119. 119An L.C.R.L.C.R. circuit contains resistance of 110Ω110\Omega and a supply of 220V220V at 300rads−1300rad{s}^{-1} angular frequency. If only capacitance is removed from the circuit, current lags behind the voltage by 45∘45^{\circ}. If on the other hand, the only the inductor is removed the current leads by 45∘45^{\circ} with the applied voltage. The R.M.S.R.M.S. current flowing in the circuit will be:JEE Main/MCQ/Medium/AC Circuits
  120. 120A transmitting station releases waves of wavelength 960m960m. A capacitor of 2.56μF2.56\mu F is used in the resonant circuit. The self-inductance of coil necessary for resonance is x×10−8Hx\times {10}^{-8}H. find xxJEE Main/Numerical/Medium/AC Circuits
  121. 121The angular frequency of alternating current in a L-C-R circuit is 100rads−1100rad{s}^{-1}. The components connected are shown in the figure. Find the value of inductance of the coil and capacity of condenser.
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  122. 122The current (i)(i) at time t=0t=0 and t=∞t=\infty respectively for the given circuit is :
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  123. 123A series LCR circuit is designed to resonate at an angular frequency ω0=105rads−1.{\omega }_{0}={10}^{5}rad{s}^{-1}. The circuit draws 16W16W power from 120V120V source at resonance. The value of resistance RR in the circuit is ________ Ω.\Omega .JEE Main/Numerical/Medium/AC Circuits
  124. 124In a series LRLR circuit, power of 400W400W is dissipated from a source of 250V,50Hz250V,50Hz. The power factor of the circuit is 0.80.8. In order to bring the power factor to unity, a capacitor of value CC is added in series to the LL and RR. Taking the value of CC as (n3π)μF\left(\dfrac{n}{3\pi }\right)\mu F, then value of nn isJEE Main/Numerical/Medium/AC Circuits
  125. 125A series L−RL-R circuit is connected to a battery of emf VV. If the circuit is switched on at t=0t=0, then the time at which the energy stored in the inductor reaches (1n)\left(\dfrac{1}{n}\right) times of its maximum value, is :JEE Main/MCQ/Medium/AC Circuits
  126. 126A 750Hz,20V(rms)750Hz,20V\left(rms\right) source is connected to a resistance of 100Ω,100\Omega , an inductance of 0.1803H0.1803H and a capacitance of 10μF10\mu F all in series. The time in which the resistance (heat capacity 2J/∘C2J/^{\circ}C ) will get heated by 10∘C.10^{\circ}C. (assume no loss of heat to the surroundings) is close to :JEE Main/MCQ/Medium/AC Circuits
  127. 127Two identical capacitors AA and B,B, charged to the same potential 5V5V are connected in two different circuits as shown below at time t=0.t=0. If the charge on capacitors AA and BB at time t=CRt=CR is QA{Q}_{A} and QB{Q}_{B} respectively, then (Here ee is the base of natural logarithm)

    JEE Main/MCQ/Medium/AC Circuits/With diagram
  128. 128In LCLC circuit the inductance L=40mHL=40mH and capacitance C=100μF.C=100\mu F. If a voltage V(t)=10sin(314t)V\left(t\right)=10sin\left(314t\right) is applied to the circuit, the current in the circuit is given as:JEE Main/MCQ/Medium/AC Circuits
  129. 129
    As shown in the figure, a battery of emf     ∈\in is connected to an inductor LL and resistance RR in series. The switch is closed at t=0.t=0. The total charge that flows from the battery, between t=0t=0 and t=tct={t}_{c} ( tc{t}_{c} is the time constant of the circuit) is:    JEE Main/MCQ/Medium/AC Circuits/With diagram
  130. 130An emf of 20V20V is applied at time t=0t=0 to a circuit containing in series 10mH10mH inductor and 5Ω5\text{Ω} resistor. The ratio of the currents at time t=∞t=\infty and at t=40st=40\text{s} is close to: (Take e2=7.389{e}^{2}=7.389 )JEE Main/MCQ/Medium/AC Circuits
  131. 131A LCRLCR circuit behaves like a clamped harmonic oscillator. Comparing it with a physical spring-mass damped oscillator having damping constant ′b′,'{b}^{'}, the correct equivalence would be:JEE Main/MCQ/Medium/AC Circuits
  132. 132Consider the LR circuit shown in the figure. If the switch S is closed at t=0t=0 then the amount of charge that passes through the battery between t=0t=0 and t=LRt=\dfrac{L}{R} is:
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  133. 133A circuit connected to an ac source of emf e=e0sin⁡⁡(100t)e={e}_{0}\sin ⁡\left(100t\right) with tt in seconds, gives a phase difference of π4\dfrac{\pi }{4} between the emf ee and current ii . Which of the following circuits will exhibit this?JEE Main/MCQ/Medium/AC Circuits
  134. 134A 2020 H\text{H} inductor coil is connected to a 1010 Ω\Omega resistance in series as shown in figure. The time at which rate of dissipation of energy (Joule's heat) across resistance is equal to the rate at which magnetic energy is stored in the inductor, is:
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  135. 135In the figure shown, a circuit contains two identical resistors with resistance R=5ΩR=5 \Omega and an inductance with L=2mH.L=2 mH. An ideal battery of 15V15V is connected in the circuit. What will be the current through the battery long after the switch is closed?

    JEE Main/MCQ/Medium/AC Circuits/With diagram
  136. 136In the circuit shown,

    the switch     S1S_{1} is closed at time t=0t=0 and the switch S2S_{2} is kept open. At some later time (t0)\left(\mathrm{t}_{0}\right), the switch S1\mathrm{S}_{1} is opened and S2\mathrm{S}_{2} is closed. the behaviour of the current I as a function of time ' t\mathrm{t} ' is given by:    JEE Main/MCQ/Medium/AC Circuits/With diagram
  137. 137An ideal capacitor of capacitance 0.2μF0.2\mu F is charged to a potential difference of 10V10V. The charging battery is then disconnected. The capacitor is then connected to an ideal inductor of self inductance 0.5mH0.5mH. The current at a time when the potential difference across the capacitor is 5V5V is:JEE Main/MCQ/Medium/AC Circuits
  138. 138A sinusoidal voltage of peak value 283V283V and angular frequency 320s−1320{s}^{-1} is applied to a series LCRLCR circuit. Given that R=5Ω,L=25mHR=5\Omega ,L=25mH and C=1000μFC=1000\mu F. The total impedance and phase difference between the voltage across the source and the current will respectively be-JEE Main/MCQ/Medium/AC Circuits
  139. 139A series LRLR circuit is connected to a voltage source with V(t)=V0sin⁡(ωt)V\left(t\right)={V}_{0}\sin \left(\omega t\right) . After a very large time, current I(t)I\left(t\right) behaves as (t0≫LR)\left({t}_{0}≫\dfrac{L}{R}\right):JEE Main/MCQ/Medium/AC Circuits
  140. 140An arc lamp requires a direct current of 10 A at 80 V to function. If it is connected to a 220 V (rms), 50 Hz AC supply, the series inductor needed for it to work is close to:JEE Main/MCQ/Medium/AC Circuits
  141. 141For the LCR circuit, shown here, the current is observed to lead the applied voltage. An additional capacitor C′{C}^{'} , when joined with the capacitor C present in the circuit, makes the power factor of the circuit unity. The capacitor C′{C}^{'} , must have been connected in:
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  142. 142An inductor (L=0.03H)(L=0.03 \text{H}) and a resistor (R=0.15kΩ)(R=0.15 \text{kΩ}) are connected in series to a battery of 15V15 \text{V} E.M.F. in a circuit shown below. The key K1{K}_{1} has been kept closed for a long time. Then at t=0t=0, K1{K}_{1} is opened and key K2{K}_{2} is closed simultaneously. At t=1mst=1 \text{ms} , the current in the circuit will be : (Take,e5≈150)\left(\text{Take},{e}^{5}\approx 150\right)

    JEE Main/MCQ/Medium/AC Circuits/With diagram
  143. 143An LCR circuit is equivalent to a damped pendulum. In an LCR circuit the capacitor is charged to Q0{Q}_{0} and then connected to the L and R as shown below:

    If a student plots graphs of the square of maximum charge     (QMax2)\left({Q}_{Max}^{2}\right) on the capacitor with time (t) for two different values L1{L}_{1} and L2(L1>L2){L}_{2}({L}_{1}\gt {L}_{2}) of L then which of the following represents this graph correctly? (plots are schematic and not drawn to scale)    JEE Main/MCQ/Medium/AC Circuits/With diagram
  144. 144When the rms voltages VL,VC{V}_{L}, {V}_{C} and VR{V}_{R} are measured respectively across the inductor L,L, the capacitor CC and the resistor RR in a series LCRLCR circuit connected to an ACAC source, it is found that the ratio VL:VC:VR=1:2:3.{V}_{L}:{V}_{C}:{V}_{R}=1:2:3. If the rms voltage of the ACAC source is 100V,100V, then VR{V}_{R} is close to :JEE Main/MCQ/Medium/AC Circuits
  145. 145In the circuit shown here, the point 'CC' is kept connected to point AA '' till the current flowing through the circuit becomes constant. Afterward, suddenly, point 'CC' is disconnected from point AA '' and connected to point 'BB' at time t=0t=0. Ratio of the voltage across resistance and the inductor at t=LRt=\dfrac{L}{R} will be equal to :

    JEE Main/MCQ/Medium/AC Circuits/With diagram
  146. 146When resonance is produced in a series LCR circuit, then which of the following is not correct?JEE Main/MCQ/Medium/AC Circuits
  147. 147In a series L−C−R\mathrm{L}-\mathrm{C}-\mathrm{R} circuit, C=10−11\mathrm{C}=10^{-11} Farad, L=10−\mathrm{L}=10^{-} 5{ }^5 Henry and R=100Ohm\mathrm{R}=100 \mathrm{Ohm}, when a constant D.C. voltage E\mathrm{E} is applied to the circuit, the capacitor acquires a charge 10−910^{-9} C. The D.C. source is replaced by a sinusoidal voltage source in which the peak voltage E0\mathrm{E}_0 is equal to the constant D.C. voltage E. At resonance the peak value of the charge acquired by the capacitor will be :JEE Main/MCQ/Medium/AC Circuits
  148. 148An LCR circuit as shown in the figure is connected to a voltage source Vac\mathrm{V}_{\mathrm{ac}} whose frequency can be varied.


    The frequency, at which the voltage across the resistor is maximum, is :    JEE Main/MCQ/Medium/AC Circuits/With diagram
  149. 149In the circuit shown here, the voltage across E\mathrm{E} and C\mathrm{C} are respectively 300 V300 \mathrm{~V} and 400 V400 \mathrm{~V}. The voltage E\mathrm{E} of the ac source is :
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  150. 150The amplitude of a damped oscillator decreases to 0.9 times its original magnitude in 5s. In another 10s it will decrease to α\alpha times its original magnitude, where α\alpha equals :JEE Main/MCQ/Medium/AC Circuits
  151. 151A resistance RR and a capacitance CC are connected in series to a battery of negligible internal resistance through a key. The key is closed at t=t= 0 . If after tt sec the voltage across the capacitance was seven times the voltage across R\mathrm{R}, the value of t\mathrm{t} isJEE Main/MCQ/Medium/AC Circuits
  152. 152In an LCRL C R circuit shown in the following figure, what will be the readings of the voltmeter across the resistor and ammeter if an a.c. source of 220 V220 \mathrm{~V} and 100 Hz100 \mathrm{~Hz} is connected to it as shown?
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  153. 153A fully charged capacitor CC with initial charge q0q_0 is connected to a coil of self inductance LL at t=0t=0. The time at which the energy is stored equally between the electric and the magnetic field is :JEE Main/MCQ/Medium/AC Circuits
  154. 154In a series LCR circuit R=200ΩR=200 \Omega and the voltage and the frequency of the main supply is 220 V220 \mathrm{~V} and 50 Hz50 \mathrm{~Hz} respectively. On taking out the capacitance from the circuit the current lags behind the voltage by 30∘30^{\circ}. On taking out the inductor from the circuit the current leads the voltage by 30∘30^{\circ}. The power dissipated in the LCR circuit isJEE Main/MCQ/Medium/AC Circuits
  155. 155An inductor (L=100mH)(L=100 \mathrm{mH}), a resistor (R=100Ω)(R=100 \Omega) and a battery (E=100 V)(E=100 \mathrm{~V}) are initially connected in series as shown in the figure. After a long time the battery is disconnected after short circuiting the points AA and BB. The current in the circuit 1 mm1 \mathrm{~mm} after the circuit is
    JEE Main/MCQ/Medium/AC Circuits/With diagram
  156. 156In a series resonant LCR circuit, the voltage across RR is 100 volts and R=1kΩR=1 \mathrm{k} \Omega with C=2μFC=2 \mu \mathrm{F}. The resonant frequency ω\omega is 200rad/s200 \mathrm{rad} / \mathrm{s}. At resonance the voltage across LL isJEE Main/MCQ/Medium/AC Circuits
  157. 157The phase difference between the alternating current and emf is π/2\pi / 2. Which of the following cannot be the constituent of the circuit?JEE Main/MCQ/Medium/AC Circuits
  158. 158In a LCR circuit capacitance is changed from CC to 2C2 C. For the resonant frequency to remain unchanged, the inductance should be changed from LL toJEE Main/MCQ/Medium/AC Circuits
  159. 159In an LCR series a.c. circuit, the voltage across each of the components, L,CL, C and RR is 50 V50 \mathrm{~V}. The voltage across the LC combination will beJEE Main/MCQ/Medium/AC Circuits
  160. 160In an oscillating LC circuit the maximum charge on the capacitor is Q. The charge on the capacitor when the energy is stored equally between the electric and magnetic field isJEE Main/MCQ/Medium/AC Circuits
  161. 161For the series LCRL C R circuit connected with 220 V,50 Hz220 \mathrm{~V}, 50 \mathrm{~Hz} a.c source as shown in the figure, the power factor is α10\frac{\alpha}{10}. The value of α\alpha is ____\_\_\_\_.
    JEE Main/MCQ/Medium/Quality and Power Factor/With diagram
  162. 162A series LRLR circuit connected with an ac source E=(25sin⁡1000t)VE=(25\sin 1000t)V has a power factor of 12\dfrac{1}{\sqrt{2}}. If the source of emf is changed to E=(20sin⁡2000t)VE=(20\sin 2000t)V, the new power factor of the circuit will be :JEE Main/MCQ/Medium/Quality and Power Factor
  163. 163A series LCR circuit with L=100πmH,C=10−3πFL=\dfrac{100}{\pi }mH,C=\dfrac{{10}^{-3}}{\pi }F and R=10ΩR=10\Omega, is connected across an AC source of 220V,50Hz220V,50Hz supply. The power factor of the circuit would be ____.JEE Main/Numerical/Medium/Quality and Power Factor
  164. 164In a series LRLR circuit with XL=R{X}_{L}=R, power factor is P1{P}_{1}. If a capacitor of capacitance CC with XC=XL{X}_{C}={X}_{L} is added to the circuit the power factor becomes P2{P}_{2}. The ratio of P1{P}_{1} to P2{P}_{2} will be :JEE Main/MCQ/Medium/Quality and Power Factor
  165. 165A series LCR circuit is connected to an AC source of 220V220V, 50Hz50Hz. The circuit contains a resistance R=80ΩR=80\Omega, an inductor of inductive reactance XL=70Ω{X}_{L}=70\Omega, and a capacitor of capacitive reactance XC=130Ω{X}_{C}=130\Omega. The power factor of circuit is x10\dfrac{x}{10}. The value of xx is:JEE Main/Numerical/Medium/Quality and Power Factor
  166. 166In a series LCR circuit, the inductive reactance (XL)\left({X}_{L}\right) is 10Ω10\Omega and the capacitive reactance (XC)\left({X}_{C}\right) is 4Ω4\Omega. The resistance (R)(R) in the circuit is 6Ω6\Omega. The power factor of the circuit is :JEE Main/MCQ/Medium/Quality and Power Factor
  167. 167In an A.C.\text{A.C.} circuit, the instantaneous e.m.f. and current are given by, E=100sin⁡30tE=100\sin 30t,I=20sin⁡(30t−π4),I=20\sin \left(30t-\dfrac{\pi }{4}\right). In one cycle of A.C.\text{A.C.}, the average power consumed by the circuit (in watt) and the watt-less current (in ampere) are, respectively:JEE Main/MCQ/Medium/Quality and Power Factor
  168. 168A series LR\mathrm{LR} circuit is connected to an ac source of frequency ω\omega and the inductive reactance is equal to 2R2 \mathrm{R}. A capacitance of capacitive reactance equal to R\mathrm{R} is added in series with L\mathrm{L} and R\mathrm{R}. The ratio of the new power factor to the old one is :JEE Main/MCQ/Medium/Quality and Power Factor
  169. 169A circuit has a resistance of 12Ω12 \Omega and an impedance of 15Ω15 \Omega. The power factor of the circuit will beJEE Main/MCQ/Medium/Quality and Power Factor
  170. 170The power factor of an ACA C circuit having resistance (R)(R) and inductance (L)(L) connected in series and an angular velocity ω\omega isJEE Main/MCQ/Medium/Quality and Power Factor
  171. 171A transformer has an efficiency of 8080% and works at 10V10V and 4kW.4kW. If the secondary voltage is 240V,240V, then the current in the secondary coil is:JEE Main/MCQ/Medium/Transformers
  172. 172A power transmission line feeds input power at 2.3kV2.3kV to a step down transformer with its primary winding having 3000turns3000\text{turns}. The output power is delivered at 230V230V by the transformer. The current in the primary of the transformer is 5A5A and its efficiency is 9090%. The winding of transformer is made of copper. The output current of transformer is ____AA.JEE Main/Numerical/Medium/Transformers
  173. 173Primary coil of a transformer is connected to 220VAC220VAC. Primary and secondary turns of the transforms are 100100 and 1010 respectively. Secondary coil of transformer is connected to two series resistances as shown in figure. The output voltage (V0)\left({V}_{0}\right) is :JEE Main/MCQ/Medium/Transformers/With diagram
  174. 174The primary side of a transformer is connected to 230V,50Hz230V,50Hz supply. The turn ratio of primary to secondary winding is 10:110:1. Load resistance connected to the secondary side is 46Ω46\Omega. The power consumed in it is:JEE Main/MCQ/Medium/Transformers
  175. 175An ideal transformer with purely resistive load operates at 12kV12kV on the primary side. It supplies electrical energy to a number of nearby houses at 120V.120V. The average rate of energy consumption in the houses served by the transformer is 60kW.60kW. The value of resistive load (Rs)({R}_{s}) required in the secondary circuit will be_________m\Omega .JEE Main/Numerical/Medium/Transformers
  176. 176Match the List-I with List-II. List I List II A AC generator I Presence of both L and C B Transformer II Electromagnetic Induction C Resonance phenomenon to occur III Quality factor D Sharpness of resonance IV Mutual Inductance Choose the correct answer from the options given below:JEE Main/MCQ/Medium/Transformers
  177. 177A transformer operating at primary voltage 8kV8kV and secondary voltage 160V160V serves a load of 80kW80kW. Assuming the transformer to be ideal with purely resistive load and working on unity power factor, the loads in the primary and secondary circuit would beJEE Main/MCQ/Medium/Transformers
  178. 178Match List - I with List - II. List-I List-II (A) AC generator (I) Detects the presence of current in the circuit (B) Galvanometer (II) Converts mechanical energy into electrical energy (C) Transformer (III) Works on the principle of resonance in AC circuit (D) Metal detector (IV) Changes an alternating voltage for smaller or greater valueJEE Main/MCQ/Medium/Transformers
  179. 179For the given circuit, comment on the type of transformer used :
    JEE Main/MCQ/Medium/Transformers/With diagram
  180. 180A common transistor radio set requires 12V12V (D.C.)\left(D.C.\right) for its operation. The D.C.D.C. source is constructed by using a transformer and a rectifier circuit, which are operated at 220V220V (A.C.)\left(A.C.\right) on standard domestic A.C.A.C. supply. The number of turns of secondary coil are 24,24, then the number of turns of primary areJEE Main/Numerical/Medium/Transformers
  181. 181Magnetic materials used for making permanent magnets (P)\left(P\right) and magnets in a transformer (T)\left(T\right) have different properties of the following, which property best matches for the type of magnet required?JEE Main/MCQ/Medium/Transformers
  182. 182A transformer consisting of 300300 turns in the primary and 150150 turns in the secondary gives output power of 2.2kW2.2kW . If the current in the secondary coil is 10A10A , then the input voltage and current in the primary coil are:JEE Main/MCQ/Medium/Transformers
  183. 183A power transmission line feeds input power at 2300V2300V to a step down transformer with its primary windings having 40004000 turns. The output power is delivered at 230V230V by the transformer. If the current in the primary of the transformer is 5A5A and its efficiency is 9090%, the output current would be:JEE Main/MCQ/Medium/Transformers
  184. 184A power transmission line feeds input power at2300V2300V to a step-down transformer with its primary windings having 40004000turns giving the output power at 230V230V. If the current in the primary coil of the transformer is 5A5A and its efficiency is 9090%, the output current would be:JEE Main/MCQ/Medium/Transformers
  185. 185Alternating current can not be measured by D.C. ammeter becauseJEE Main/MCQ/Medium/Transformers
  186. 186The core of any transformer is laminated so as toJEE Main/MCQ/Medium/Transformers
  187. 187In a transformer, number of turns in the primary coil are 140 and that in the secondary coil are 280. If current in primary coil is 4 A4 \mathrm{~A}, then that in the secondary coil isJEE Main/MCQ/Medium/Transformers
  188. 188An inductor of self inductance 1 H connected in series with a resistor of 100πohm100 \pi \mathrm{ohm} and an ac supply of 100π100 \pi volt, 50 Hz. Maximum current flowing in the circuit is ________ A.JEE Main/Numerical/Medium/Parallel AC Circuits
  189. 189Three identical resistors with resistance R=12ΩR=12\Omega and two identical inductors with sell inductance L=5mHL=5mH are connected to an ideal battery with emf of 12V12V as shown in figure. The current through the battery long after the switch has been closed will be________AA.
    JEE Main/Numerical/Medium/Parallel AC Circuits/With diagram
  190. 190The figure shows a circuit that contains four identical resistors with resistance R=2.0Ω,R=2.0\Omega , two identical inductors with inductance L=2.0mHL=2.0mH and an ideal battery with E.M.F. E=9V.E=9V. The current ii just after the switch SS is closed will be:
    JEE Main/MCQ/Medium/Parallel AC Circuits/With diagram

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