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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 27 August 2021, Shift 2, Physics Q21

Question 21 of 90 in this shift, Physics question 21 of 30, Section B.

The ratio of the equivalent resistance of the network (shown in figure) between the points a and b when switch is open and switch is closed is x:8x:8. The value of xx is __________.

The figure, in words

Network between terminals a (left) and b (right). Top branch: resistor R then resistor 2R in series; bottom branch: resistor 2R then resistor R in series. A switch S connects the junction between the two top resistors to the junction between the two bottom resistors.

Official answer

9

NTA final key.

Chapter
Current Electricity
Topic
Kirchhoff's Laws
Idea tested
Circuit Symmetry Analysis

Same idea in other shifts

Asked 8× in all
  1. 9 Apr 2024, Shift 2 · Q43The effective resistance between AA and BB, if resistance of each resistor is RR, will be :MediumSingle correctHas a figure
  2. 10 Apr 2023, Shift 1 · Q50The equivalent resistance of the circuit shown below between points aa and bb is :MediumDiagram basedHas a figure
  3. 25 Jun 2022, Shift 1 · Q58The total current supplied to the circuit as shown in figure by the 5 V battery is __________ A.MediumNumerical valueHas a figure
  4. 26 Jun 2022, Shift 2 · Q41The equivalent resistance between points A and B in the given network is :MediumDiagram basedHas a figure
  5. 28 Jun 2022, Shift 2 · Q55All resistances in figure are 1 Ω each. The value of current ‘I’ is a5\frac{a}{5} A. The value of a is __________.MediumNumerical valueHas a figure
  6. 26 Aug 2021, Shift 1 · Q12In the given figure, the emf of the cell is 2.2 V and if internal resistance is 0.6 Ω\Omega. Calculate the power dissipated in the whole…MediumDiagram basedHas a figure
  7. 26 Feb 2021, Shift 1 · Q15Five equal resistances are connected in a network as shown in figure. The net resistance between the points A and B is :MediumDiagram basedHas 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.