STD 12 -Alternating current PYQs: JEE Mains Physics – Page 2

Showing 51–100 of 142 questions

51. 51. As per the given graph choose the correct representation for curve \(A\) and curve \(B\).Where \(X _{ C }=\) reactance of pure capacitive circuit connected with \(A.C.\) source \(X _{ L }=\) reactance of pure inductive circuit connected with \(A.C.\) source \(R =\) impedance of pure resistive circuit connected with \(A.C.\) source \(Z =\) Impedance of the LCR series circuit \(\}\)
    2023 Medium
52. 52. For the given figures, choose the correct options:
    2023 Medium
53. 53. Given 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 2023 Medium
54. 54. Given 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 \(AC\) 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 : 2023 Medium
55. 55. Given below are two statements Statement \(I\) : When the frequency of an \(a.c.\) 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 2023 Medium
56. 56. In a series \(L R\) circuit with \(X_L=R\). power factor is \(P_1\). If a capacitor of capacitance \(C\) with \(X _{ C }= X _{ L }\) is added to the circuit the power factor becomes \(P _2\). The ratio of \(P_1\) to \(P_2\) will be : 2023 Medium
57. 57. In an \(LC\) oscillator, if values of inductance and capacitance become twice and eight times, respectively, then the resonant frequency of oscillator becomes \(x\) times its initial resonant frequency \(\omega_0\). The value of \(x\) is: 2023 Easy
58. 58. In the circuit shown in the figure, the ratio of the quality factor and the band width is \(.............\) s.
    2023 Medium
59. 59. In the given circuit, rms value of current \(\left( I _{ rms }\right)\) through the resistor \(R\) is :\(..........\,A\)
    2023 Medium
60. 60. Match 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: 2023 Medium
61. 61. A \(110 \; V , 50 \; Hz , AC\) source is connected in the circuit (as shown in figure). The current through the resistance \(55 \; \Omega\), at resonance in the circuit, will be \(\dots \; A\).
    2022 Medium
62. 62. A capacitor of capacitance \(500\,\mu F\) is charged completely using a dc supply of \(100\,V\). It is now connected to an inductor of inductance \(50\,mH\) to form an \(LC\) circuit. The maximum current in \(LC\) circuit will be \(.........A\). 2022 Medium
63. 63. A circuit element \(X\) when connected to an a.c. supply of peak voltage \(100\,V\) gives a peak current of \(5\,A\) which is in phase with the voltage. A second element \(Y\) when connected to the same a.c. supply also gives the same value of peak current which lags behind the voltage by \(\frac{\pi}{2}\). If \(X\) and \(Y\) are connected in series to the same supply, what will be the rms value of the current in ampere? 2022 Medium
64. 64. A direct current of \(4\,A\) and an alternating current of peak value \(4\,A\) flow through resistance of \(3\,\Omega\) and \(2\,\Omega\) respectively. The ratio of heat produced in the two resistances in same interval of time will be. 2022 Medium
65. 65. A resistance of \(40 \,\Omega\) is connected to a source of alternating current rated \(220\, V , 50 Hz\). Find the time taken by the current to change from its maximum value to \(ms\) value 2022 Hard
66. 66. A series \(L C R\) circuit has \(L=0.01\,H, R=10\,\Omega\) and \(C =1\,\mu F\) and it is connected to ac voltage of amplitude \(\left( V _{ m }\right) 50\,V\). At frequency \(60 \%\) lower than resonant frequency, the amplitude of current will be approximately \(...............\,mA\) 2022 Hard
67. 67. A sinusoidal voltage \(V(t)=210\,\sin 3000 t\) volt is applied to a series \(LCR\) circuit in which \(L =10\) \(mH , C =25 \mu F\) and \(R =100 \Omega\). The phase difference \((\Phi)\) between the applied voltage and resultant current will be 2022 Hard
68. 68. A telegraph line of length \(100 \,km\) has a capacity of \(0.01\,\mu F / km\) and it carries an alternating current at \(0.5 \,kilo \,cycle \,per \,second\). If minimum impedance is required, then the value of the inductance that needs to be introduced in series is__________ \(m H\). \(\text { (if } \pi=\sqrt{10})\) 2022 Medium
69. 69. An \(AC\) source is connected to an inductance of \(100\,mH\) a capacitance of \(100\,\mu F\) and a resistance of \(120\,\Omega\) as shown in figure. The time in which the resistance having a thermal capacity \(2\,J^{\circ } C\) will get heated by \(16^{\circ} C\) is ..........\(S\)
    2022 Hard
70. 70. An alternating \(emf\) \(E =440 \sin 100 \pi t\) is applited to a circuit containing an inductance of \(\frac{\sqrt{2}}{\pi} H\). If an a.c. ammeter is connected in the circuit, its reading will be \(.......A\) 2022 Hard
71. 71. An inductor of \(0.5 \,mH\), a capacitor of \(200 \,\mu F\) and a resistor of \(2 \,\Omega\) are connected in series with a \(220 \,V\) ac source. If the current is in phase with the emf, the frequency of ac source will be ................ \(\times 10^{2} \,Hz\) 2022 Hard
72. 72. As shown in the figure an inductor of inductance \(200\, mH\) is connected to an \(AC\) source of emf \(220 \,V\) and frequency \(50 \,Hz\). The instantaneous voltage of the source is \(0\, V\) when the peak value of current is \(\frac{\sqrt{a}}{\pi} A\). The value of a is..........
    2022 Medium
73. 73. For a series \(LCR\) circuit, \(I\) vs \(\omega\) curve is shown \((A)\) To the left of \(\omega_{r}\), the circuit is mainly capacitive. \((B)\) To the left of \(\omega_{r}\), the circuit is mainly inductive. \((C)\) At \(\omega_{r}\), impedance of the circuit is equal to the resistance of the circuit. \((D)\) At \(\omega_{t}\), impedance of the circuit is \(0\). Choose the most appropriate answer from the options given below
    2022 Hard
74. 74. Given 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 2022 Medium
75. 75. If wattless current flows in the \(AC\) circuit, then the circuit is 2022 Medium
76. 76. In a series \(L R\) circuit \(X_{L}=R\) and power factor of the circuit is \(P _{1}\). When capacitor with capacitance \(C\) such that \(X _{ L }= X _{ C }\) is put in series, the power factor becomes \(P_{2}\). The ratio \(\frac{ P _{1}}{ P _{2}}\) is 2022 Medium
77. 77. In a series \(LCR\) circuit, the inductance, capacitance and resistance are \(L =100\, mH , C =100 \mu F\) and \(R =\) \(10 \Omega\) respectively. They are connected to an \(AC\) source of voltage \(220\, V\) and frequency of \(50\, Hz\). The approximate value of current in the circuit will be.....\(A.\)
    2022 Medium
78. 78. In the given circuit, the magnitude of \(V_{L}\) and \(V_{C}\) are twice that of \(V_{R}\). Given that \(f=50\,Hz\), the inductance of the coil is \(\frac{1}{ K \pi}\,mH\). The value of \(K\) is_________
    2022 Medium
79. 79. Match 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 value

    Choose the correct answer from the options given below 2022 Medium
80. 80. The current flowing through an ac circuit is given by \(I=5 \sin (120 \pi t) A\) How long will the current take to reach the peak value starting from zero? 2022 Medium
81. 81. The effective current \(I\) in the given circuit at very high frequencies will be \(.......A\)
    2022 Hard
82. 82. The equation of current in a purely inductive circuit is \(5 \sin \left(49 \pi t-30^{\circ}\right)\). If the inductance is \(30\,mH\) then the equation for the voltage across the inductor, will be.\(\left\{\right.\) Let \(\left.\pi=\frac{22}{7}\right\}\) 2022 Medium
83. 83. The frequencies at which the current amplitude in an \(LCR\) series circuit becomes \(\frac{1}{\sqrt{2}}\) times its maximum value, are \(212\,rad\,s ^{-1}\) and \(232\,rad\,s ^{-1}\). The value of resistance in the circuit is \(R =5 \Omega\). The self inductance in the circuit is \(.........mH\) 2022 Medium
84. 84. The rms value of conduction current in a parallel plate capacitor is \(6.9\,\mu\,A\). The capacity of this capacitor, if it is connected to \(230 V\) ac supply with an angular frequency of \(600\,rad / s\), will be \(....\,pF\) 2022 Medium
85. 85. To increase the resonant frequency in series \(LCR\) circuit, 2022 Medium
86. 86. To light, a \(50\,W , 100\,V\) lamp is connected, in series with a capacitor of capacitance \(\frac{50}{\pi \sqrt{ x }} \mu F\), with \(200 V , 50 Hz AC\) source. The value of \(x\) will be........ 2022 Hard
87. 87. When you walk through a metal detector carrying a metal object in your pocket, it raises an alarm. This phenomenon works on 2022 Medium
88. 88. A \(0.07\,{H}\) inductor and a \(12 \,\Omega\) resistor are connected in series to a \(220 \,{V}, 50 \,{Hz}\) ac source. The approximate current in the circuit and the phase angle between current and source voltage are respectively. [Take \(\pi\) as \(\left.\frac{22}{7}\right]\) 2021 Hard
89. 89. A \(100 \,\Omega\) resistance, a \(0.1\, \mu {F}\) capacitor and an inductor are connected in series across a \(250 \,{V}\) supply at variable frequeny. Calculate the value of inductance of inductor at which resonance will occur. Given that the resonant frequency is \(60\, {Hz}\). (In \({H}\)) 2021 Medium
90. 90. A resonance circuit having inductance and resistance \(2 \times 10^{-4} H\) and \(6.28 \Omega\) respectively oscillates at \(10\, MHz\) frequency. The value of quality factor of this resonator is ......... \([\pi=3.14]\) 2021 Medium
91. 91. A series \(LCR\) circuit driven by \(300\, {V}\) at a frequency of \(50 \,{Hz}\) contains a resistance \({R}=3 \,{k} \Omega\), an inductor of inductive reactance \(X_{L}=250 \,\pi \Omega\) and an unknown capacitor. The value of capacitance to maximize the average power should be : (Take \(\pi^{2}=10\) ) (in \(\mu {F}\)) 2021 Medium
92. 92. A series \(LCR\) circuit is designed to resonate at an angular frequency \(\omega_{0}=10^{5} \,rad / s\). The circuit draws \(16\, W\) power from \(120\, V\) source at resonance. The value of resistance \('R'\) in the circuit is ...... \(\Omega\). 2021 Medium
93. 93. A series \(LCR\) circuit of \(R=5\, \Omega, L=20\, {mH}\) and \({C}=0.5 \,\mu \,{F}\) is connected across an \({AC}\) supply of \(250\, V\), having variable frequency. The power dissipated at resonance condition is \(.....\,\times 10^{2}\, {W}\) 2021 Medium
94. 94. A sinusoidal voltage of peak value \(250\, V\) is applied to a series \(LCR\) circuit, in which \(R =8 \Omega, L =24\, mH\) and \(C =60 \mu F\). The value of power dissipated at resonant condition is \('x'\, kW\). The value of \(x\) to the nearest integer is ............. 2021 Medium
95. 95. A transmitting station releases waves of wavelength \(960\, m\). A capacitor of \(2.56\, \mu F\) is used in the resonant circuit. The self inductance of coil necessary for resonance is ............. \(-\times 10^{-8} H\) 2021 Medium
96. 96. An ac circuit has an inductor and a resistor of resistance \({R}\) in series, such that \({X}_{{L}}=3 {R}\). Now, a capacitor is added in series such that \({X}_{{C}}=2 {R}\). The ratio of new power factor with the old power factor of the circuit is \(\sqrt{5}: {x}\). The value of \({x}\) is ...... . 2021 Medium
97. 97. An \(AC\) current is given by \(I = I _{1} \sin \omega t + I _{2} \cos \omega t\). A hot wire ammeter will give a reading 2021 Hard
98. 98. An \(AC\) source rated \(220\, V , 50\, Hz\) is connected to a resistor. The time taken by the current to change from its maximum to the rms value is 2021 Medium
99. 99. An alternating current is given by the equation \(i=i_{1} \sin \omega t+i_{2} \cos \omega t\). The rms current will be 2021 Hard
100. 100. An \(LCR\) circuit contains resistance of \(110 \, \Omega\) and a supply of \(220\, V\) at \(300 \,rad / s\) angular frequency. If only capacitance is removed from the circuit, current lags behind the voltage by \(45^{\circ}\). If on the other hand, only inductor is removed the current leads by \(45^{\circ}\) with the applied voltage. The rms current flowing in the circuit will be ...... \(A\) 2021 Hard

No questions on this page match these filters. Clear filters