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Alternating Current

JEE Main 2026 (Online) 2nd April Evening ShiftMCQMedium📈 Topic in 16% papers+4−1
Ques. 1JEE Main 2026, 2 April (Evening Shift)

The figure given below shows an LCR series circuit with two switches S1 and S2. When switch S1 is closed keeping S2 open, the phase difference ( ) between the current and source voltage is 30° and phase difference is 60° when S2 is closed keeping S1 open. The value of (3L1-L2) is H. [figure]

  1. 92
  2. 29
  3. 13
  4. 3

Answer

(2) 29

Solution

From the figure, S1 is across L2 and S2 is across L1, and a closed switch shorts that inductor.

Here = 300 rad/s and XC = 1 C = 1300 100 10-6 = 1003 Ω.

With S1 closed only L1 is in the circuit, so 30° = L1 - XCR … (i)

With S2 closed only L2 is in the circuit, so 60° = L2 - XCR … (ii)

Dividing (ii) by (i): L2 - XC L1 - XC = 31/ 3 = 3

L2 - XC = 3 L1 - 3XC

(3L1 - L2) = 2XC

3L1 - L2 = 2XC = 2 100/3300 = 29 H

Answer: (2)

Keep practising — Alternating Current

Ques. 2JEE Main 2026, 28 January (Morning Shift)

The electric current in the circuit is given as i = io(t/T). The r.m.s current for the period t = 0 to t = T is .

  1. io 2
  2. io 3
  3. io
  4. io 6
Ques. 3JEE Main 2026, 28 January (Evening Shift)

An 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 . ( = 3.14)

Ques. 4JEE Main 2026, 24 January (Morning Shift)

For the series LCR circuit connected with 220 V, 50 Hz a.c. source as shown in the figure, the power factor is 10. The value of is . [figure]

  1. 4
  2. 8
  3. 6
  4. 10
Ques. 5JEE Main 2026, 23 January (Morning Shift)

Using a variable frequency a.c. voltage source the maximum current measured in the given LCR circuit is 50 mA for V = 5 (100t). The values of L and R are shown in the figure. The capacitance of the capacitor (C) used is . [figure]

Ques. 6JEE Main 2026, 21 January (Evening Shift)

A capacitor C is first charged fully with potential difference of V0 and disconnected from the battery. The charged capacitor is connected across an inductor having inductance L. In t s, 25% of the initial energy in the capacitor is transferred to the inductor. The value of t is s.

  1. LC3
  2. LC2
  3. LC2
  4. LC6
Ques. 7JEE Main 2025, 7 April (Morning Shift)

An ac current is represented as i = 5 2 + 10 (650 t + 6 ) Amp The r.m.s. value of the current is

  1. 10 Amp
  2. 5 2 Amp
  3. 100 Amp
  4. 50 Amp
Ques. 8JEE Main 2025, 7 April (Morning Shift)

For ac circuit shown in figure, R = 100 k and C = 100 pF and the phase difference between Vin and (VB - VA) is 90 . The input signal frequency is 10x rad/sec, where 'x' is . [figure]

Ques. 9JEE Main 2025, 7 April (Evening Shift)

An inductor of reactance 100 , a capacitor of reactance 50 , and a resistor of resistance 50 are connected in series with an AC source of 10 V, 50 Hz. Average power dissipated by the circuit is W.

Ques. 10JEE Main 2025, 4 April (Morning Shift)

An alternating current is represented by the equation, i = 100 2 (100 t) ampere. The RMS value of current and the frequency of the given alternating current are

  1. 100 2 A, 100 Hz
  2. 50 2 A, 50 Hz
  3. 100 2 A, 100 Hz
  4. 100 A, 50 Hz
Ques. 11JEE Main 2025, 4 April (Evening Shift)

An inductor of self inductance 1 H is connected in series with a resistor of 100 ohm and an ac supply of 100 volt, 50 Hz. Maximum current flowing in the circuit is A.

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