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Top Previous Year Questions - Alternating Current

Question

A LCR circuit behaves like a clamped harmonic oscillator. Comparing it with a physical spring-mass damped oscillator having damping constant 'b', the correct equivalence would be:

JEE Main 2020 (07 Jan Shift 1)

Options

  • A: Lm,Ck,Rb
  • B: L1b,C1m,R1k
  • C: Lk,Cb,Rm
  • D: Lm,C1k,Rb
Explaination

Question

In a circuit consisting of a capacitance and a generator with alternating emf, Eg=Egosinωt, VC and IC are the voltage and current. Correct phasor diagram for such circuit is

JEE Main 2021 (22 Jul Shift 1)

Options

  • A:
  • B:
  • C:
  • D:
Explaination

Question

Match List-I with List-II.

  List - I   List - II
(a) ωL>1ωC (i) Current is in phase with emf
(b) ωL=1ωC (ii) Current lags behind the applied emf
(c) ωL<1ωC (iii) Maximum current occurs
(d) Resonant frequency (iv) Current leads the emf

Choose the correct answer from the options given below.

JEE Main 2021 (22 Jul Shift 1)

Options

  • A: (a) - (ii) ; (b) - (i) ; (c) - (iv) ; (d) - (iii)
  • B: (a) - (ii) ; (b) - (i) ; (c) - (iii) ; (d) - (iv)
  • C: (a) - (iii) ; (b) - (i) ; (c) - (iv); (d) - (ii)
  • D: (a) - (iv) ; (b) - (iii) ; (c) - (ii); (d) - (i)
Explaination

Question

A series LCR circuit driven by 300 V at a frequency of 50 Hz contains a resistance R=3 , an inductor of inductive reactance XL=250π Ω and an unknown capacitor. The value of capacitance to maximise the average power should be:
take π2=10

JEE Main 2021 (26 Aug Shift 1)

Options

  • A: 400 μF
  • B: 4 μF
  • C: 40 μF
  • D: 25 μF
Explaination

Question

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

JEE Main 2022 (25 Jun Shift 1)

Options

  • A: A-II,B-I,C-IV,D-III
  • B: A-II,B-I,C-III,D-IV
  • C: A-III,B-IV,C-II,D-I
  • D: A-III,B-I,C-II,D-IV
Explaination

Question

A series LCR circuit has L=0.01 H,R=10 Ω and C=1 μF and it is connected to ac voltage of amplitude Vm 50 V. At frequency 60% lower than resonant frequency, the amplitude of current will be approximately

JEE Main 2022 (27 Jul Shift 2)

Options

  • A: 466 mA
  • B: 312 mA
  • C: 238 mA
  • D: 196 mA
Explaination

Question

For a series LCR circuit, I vs ω curve is shown 

(a) To the left of ωr, the circuit is mainly capacitive.
(b) To the left of ωr, the circuit is mainly inductive.
(c) At ωr, impedance of the circuit is equal to the resistance of the circuit.
(d) At ωr, impedance of the circuit is 0.

Choose the most appropriate answer from the options given below.

JEE Main 2022 (29 Jun Shift 1)

Options

  • A: (a) and (d) only
  • B: (b) and (d) only
  • C: (a) and (c) only
  • D: (b) and (c) only
Explaination

Question

A telegraph line of length 100 km has a capacity of 0.01 μF km-1 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 _____ mH. (If π=10)

JEE Main 2022 (28 Jun Shift 1)

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Explaination

Question

In a series LR circuit with XL=R, power factor is P1. If a capacitor of capacitance C with XC=XL is added to the circuit the power factor becomes P2. The ratio of P1 to P2 will be :

JEE Main 2023 (30 Jan Shift 1)

Options

  • A: 1:3
  • B: 1:2
  • C: 1:1
  • D: 1:2
Explaination

Question

A series LCR circuit is connected to an ac source of 220 V, 50 Hz. The circuit contain a resistance R=100 Ω and an inductor of inductive reactance XL=79.6 Ω. The capacitance of the capacitor needed to maximize the average rate at which energy is supplied will be ______ μF.

JEE Main 2023 (01 Feb Shift 1)

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Explaination

Question

When a $d c$ voltage of $100 \mathrm{~V}$ is applied to an inductor, a $d c$ current of $5 \mathrm{~A}$ flows through it. When an ac voltage of $200 \mathrm{~V}$ peak value is connected to inductor, its inductive reactance is found to be $20 \sqrt{3} \Omega$. The power dissipated in the circuit is _______ W.

JEE Main 2024 (06 Apr Shift 1)

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Explaination

Question

A coil of negligible resistance is connected in series with $90 \Omega$ resistor across $120 \mathrm{~V}, 60 \mathrm{~Hz}$ supply. A voltmeter reads $36 \mathrm{~V}$ across resistance. Inductance of the coil is :

JEE Main 2024 (08 Apr Shift 2)

Options

  • A: $0.286 \mathrm{H}$
  • B: $0.76 \mathrm{H}$
  • C: $2.86 \mathrm{H}$
  • D: $0.91 \mathrm{H}$
Explaination

Question

An alternating emf $\mathrm{E}=110 \sqrt{2} \sin 100 \mathrm{t}$ volt is applied to a capacitor of $2 \mu \mathrm{F}$, the rms value of current in the circuit is _____$\mathrm{mA}$,

JEE Main 2024 (08 Apr Shift 2)

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Explaination

Question

A capacitor of reactance $4 \sqrt{3} \Omega$ and a resistor of resistance $4 \Omega$ are connected in series with an ac source of peak value $8 \sqrt{2} \mathrm{~V}$. The power dissipation in the circuit is ________ W.

JEE Main 2024 (09 Apr Shift 2)

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Explaination

Question

In the given figure, the charge stored in 6μF capacitor, when points A and B are joined by a connecting wire is _______μC.

JEE Main 2024 (29 Jan Shift 2)

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Explaination

Question

The primary side of a transformer is connected to 230 V, 50 Hz supply. The turn ratio of primary to secondary winding is 10 : 1. Load resistance connected to the secondary side is 46 Ω. The power consumed in it is:

JEE Main 2024 (27 Jan Shift 2)

Options

  • A: 12.5 W
  • B: 10.0 W
  • C: 11.5 W
  • D: 12.0 W
Explaination

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