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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceDiagram basedMediumMulti-step

JEE Main 2 September 2020, Shift 2, Physics Q13

Question 13 of 75 in this shift, Physics question 13 of 25.

A wire carrying current I is bent in the shape ABCDEFA as shown, where rectangle ABCDA and ADEFA are perpendicular to each other. If the sides of the rectangles are of lengths a and b, then the magnitude and direction of magnetic moment of the loop ABCDEFA is :

The figure, in words

3-D axes drawn with dashed lines: Z up, Y to the right, X towards the lower left, meeting at O. Points A and B lie along the X direction near the bottom (A near the X axis, length A to B marked a, arrow on AB pointing towards B), B to C marked b along the base, C at the right with an arrow on CD pointing towards D (leftwards), D near O. A vertical edge from D up to E carries an upward arrow labelled I; E to F is a slanted edge with an arrow pointing towards F, labelled I; F above A, with a downward arrow on FA.
  1. (1)2\sqrt{2} abI, along (j^5+2k^5)\left(\frac{\hat{j}}{\sqrt{5}} + \frac{2\hat{k}}{\sqrt{5}}\right)
  2. (2)abI, along (j^5+2k^5)\left(\frac{\hat{j}}{\sqrt{5}} + \frac{2\hat{k}}{\sqrt{5}}\right)
  3. (3)2\sqrt{2} abI, along (j^2+k^2)\left(\frac{\hat{j}}{\sqrt{2}} + \frac{\hat{k}}{\sqrt{2}}\right)Official answer
  4. (4)abI, along (j^2+k^2)\left(\frac{\hat{j}}{\sqrt{2}} + \frac{\hat{k}}{\sqrt{2}}\right)

Official answer

Option 3

NTA final key (Sep 2020).

Chapter
Moving Charges and Magnetism
Topic
Magnetic Dipole Moment
Idea tested
Magnetic Moment of Non-Planar Loops

Same topic in other shifts

All Magnetic Dipole Moment questions
  1. 4 Apr 2026, Shift 1 · Q41An insulated wire is wound so that it forms a flat coil with N=200N=200 turns. The radius of the innermost turn is r1=3r_1=3 cm, and of the…MediumSingle correct
  2. 4 Apr 2026, Shift 2 · Q48Two identical small bar magnets each of dipole moment 353\sqrt5 J/T are placed at a center to center separation of 10 cm, with their axes…MediumNumerical valueHas a figure
  3. 4 Apr 2026, Shift 2 · Q49A circular coil of radius 2 cm and 125 turns carries a current of 1 A. The coil is placed in a uniform magnetic field of magnitude 0.4 T.…EasyNumerical value
  4. 8 Apr 2026, Shift 2 · Q39A current carrying circular loop of radius 2 cm with unit normal n^=k^+i^2\hat{n} = \frac{\hat{k} + \hat{i}}{\sqrt{2}} is placed in a magnetic…MediumSingle correct
  5. 3 Apr 2025, Shift 2 · Q36A magnetic dipole experiences a torque of 80380\sqrt{3} N m when placed in uniform magnetic field in such a way that dipole moment makes…EasySingle correct
  6. 4 Apr 2024, Shift 1 · Q57The magnetic field existing in a region is given by B⃗=0.2 (1+2x)k^ T\vec{B} = 0.2\,(1 + 2x)\hat{k}\,\mathrm{T}. A square loop of edge 50 cm carrying 0.5…HardNumerical 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.