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Saturday, 31 October

JEE Main 2026 · PhysicsMultiple choiceSingle correctHardMulti-step

JEE Main 2 April 2026, Shift 2, Physics Q42

Question 42 of 75 in this shift, Physics question 17 of 25, Section A.

The figure given below shows an LCR 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° and phase difference is 60° when S2S_2 is closed keeping S1S_1 open. The value of (3L1−L2)(3L_1 - L_2) is

The figure, in words

[figure: LCR circuit with capacitor C=100μF, resistor R, two inductors L1 and L2, switches S1 and S2, and AC source v=V_0 sin(300t)]
  1. (1)92\frac{9}{2} H
  2. (2)29\frac{2}{9} HOfficial answer
  3. (3)13\frac{1}{3} H
  4. (4)33 H

Official answer

Option 2

NTA final key.

Chapter
Alternating Current
Topic
Phasor Diagrams
Idea tested
Impedance Triangle Construction

Same idea in other shifts

Asked 9× in all
  1. 4 Apr 2026, Shift 1 · Q50An 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…MediumNumerical value
  2. 5 Apr 2026, Shift 1 · Q44An 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…MediumSingle correct
  3. 5 Apr 2024, Shift 1 · Q57An ac source is connected in given series LCR circuit. The rms potential difference across the capacitor of 20 μF20\ \mu\mathrm{F} is…MediumNumerical valueHas a figure
  4. 9 Apr 2024, Shift 1 · Q43A bulb and a capacitor are connected in series across an ac supply. A dielectric is then placed between the plates of the capacitor. The…MediumSingle correct
  5. 27 Jul 2022, Shift 2 · Q44A series LCR circuit has L = 0.01 H, R = 10 Ω\Omega and C = 1 μ\muF and it is connected to ac voltage of amplitude (Vm\mathrm{V_m}) 50…MediumSingle correct
  6. 25 Jun 2022, Shift 2 · Q42A sinusoidal voltage V(t)V(t) = 210 sin 3000 tt volt is applied to a series LCR circuit in which LL = 10 mHmH, CC =25 µFF and RR = 100…MediumSingle correct
  7. 28 Jun 2022, Shift 1 · Q54An AC source is connected to an inductance of 100 mH, a capacitance of 100 μ\mu F and a resistance of 120 Ω\Omega as shown in figure.…MediumNumerical valueHas a figure
  8. 3 Sep 2020, Shift 1 · Q15A 750 Hz, 20 V (rms) source is connected to a resistance of 100 Ω\Omega, an inductance of 0.1803 H and a capacitance of 10 μ\muF all in…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.