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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueEasyCalculation

JEE Main 18 March 2021, Shift 2, Physics Q26

Question 26 of 90 in this shift, Physics question 26 of 30, Section B.

Consider a 72 cm long wire AB as shown in the figure. The galvanometer jockey is placed at P on AB at a distance xx cm from A. The galvanometer shows zero deflection. The value of xx, to the nearest integer, is _________.

The figure, in words

Rectangular circuit: top branch has a 12 Ω resistor (left) and a 6 Ω resistor (right) with a junction point C between them; from C a branch with a galvanometer G leads down to the jockey at point P on the thick wire AB along the bottom (A at left end, B at right end); the distance from A to P is marked x with a double-headed arrow; a cell/battery symbol is on the bottom side of the rectangle below the wire.

Official answer

48

NTA final key.

Chapter
Current Electricity
Topic
Wheatstone Bridge
Idea tested
Meter Bridge Principles

Same idea in other shifts

Asked 7× in all
  1. 1 Feb 2024, Shift 2 · Q50In a metre-bridge when a resistance in the left gap is 2 Ω2\,\Omega and unknown resistance in the right gap, the balance length is found to…MediumSingle correct
  2. 31 Jan 2024, Shift 2 · Q49The resistance per centimeter of a meter bridge wire is rr, with X ΩX\ \Omega resistance in left gap. Balancing length from left end is at…MediumSingle correct
  3. 26 Jul 2022, Shift 1 · Q56Resistances are connected in a meter bridge circuit as shown in the figure. The balancing length l1l_1 is 40 cm. Now an unknown resistance…MediumNumerical valueHas a figure
  4. 27 Jul 2022, Shift 1 · Q51In a meter bridge experiment, for measuring unknown resistance 'S', the null point is obtained at a distance 30 cm from the left side as…EasyNumerical valueHas a figure
  5. 27 Jul 2022, Shift 2 · Q52In the given figure of meter bridge experiment, the balancing length AC corresponding to null deflection of the galvanometer is 40 cm. The…MediumNumerical valueHas a figure
  6. 9 Jan 2020, Shift 2 · Q23In a meter bridge experiment S is a standard resistance. R is a resistance wire. It is found that balancing length is l=25l = 25 cm. If R is…EasyNumerical 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.