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Saturday, 31 October

JEE Main 2026 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 2 April 2026, Shift 1, Physics Q39

Question 39 of 75 in this shift, Physics question 14 of 25, Section A.

Two identical long current carrying wires are bent into the shapes shown in the following figures. If the magnitude of magnetic fields at the centres P and Q of a semicircular arc are B1B_1 and B2B_2 respectively, then the ratio B1B2\frac{B_1}{B_2} is _______.

The figure, in words

(I) Two long parallel straight wires carrying current I in opposite directions, joined by a semicircular arc of radius r with centre P. (II) A long straight wire carrying current I coming in horizontally, then a semicircular arc of radius r with centre Q, then a long straight wire going vertically downward carrying I.
  1. (1)2+π1+π\frac{2+\pi}{1+\pi}Official answer
  2. (2)1+π1−π\frac{1+\pi}{1-\pi}
  3. (3)2+π1−π\frac{2+\pi}{1-\pi}
  4. (4)1+π2−π\frac{1+\pi}{2-\pi}

Official answer

Option 1

NTA final key.

Chapter
Moving Charges and Magnetism
Topic
Biot-Savart Law
Idea tested
Superposition of magnetic fields

Same idea in other shifts

Asked 5× in all
  1. 6 Apr 2026, Shift 2 · Q38A current of 30 A each flows in opposite directions in two conducting wires, placed parallel to each other at a distance of 8 cm. The…EasySingle correct
  2. 6 Apr 2023, Shift 1 · Q57Two identical circular wires of radius 20 cm and carrying current 2\sqrt2 A are placed in perpendicular planes as shown in figure. The…MediumNumerical valueHas a figure
  3. 27 Jun 2022, Shift 2 · Q43Two long parallel conductors S1_1 and S2_2 are separated by a distance 10 cm and carrying currents of 4A and 2A respectively. The…HardSingle correctHas a figure
  4. 8 Jan 2020, Shift 2 · Q12A very long wire ABDMNDC is shown in figure carrying current I. AB and BC parts are straight, long and at right angle. At D wire forms a…HardDiagram 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.