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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceDiagram basedHardMulti-step

JEE Main 25 February 2021, Shift 1, Physics Q17

Question 17 of 90 in this shift, Physics question 17 of 30, Section A.

The angular frequency of alternating current in a L-C-R circuit is 100 rad/s. The components connected are shown in the figure. Find the value of inductance of the coil and capacity of condenser.

The figure, in words

A circuit loop with an AC source symbol at the bottom. Left side: a capacitor labelled C with '10 V' beside it. Top-left: a resistor labelled R = 60 Ω with '15 V' printed beneath it. Two branches hang from the top wire in parallel: the middle branch has a resistor labelled R' = 40 Ω in series with a small curved open-arc symbol drawn below it; the right branch has a coil labelled L with '20 V' beside it.
  1. (1)1.33 H and 250 μ250\ \muF
  2. (2)1.33 H and 150 μ150\ \muF
  3. (3)0.8 H and 150 μ150\ \muF
  4. (4)0.8 H and 250 μ250\ \muFOfficial answer

Official answer

Option 4

NTA final key.

Chapter
Alternating Current
Topic
Phasor Diagrams
Idea tested
Series Phasor Addition

Same idea in other shifts

Asked 3× in all
  1. 29 Jul 2022, Shift 2 · Q38A 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.…MediumSingle correct
  2. 28 Jun 2022, Shift 2 · Q54In the given circuit, the magnitude of VL_L and VC_C are twice that of VR_R. Given that ff=50 Hz, the inductance of the coil is…MediumNumerical valueHas a figure

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.