JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 26 August 2021, Shift 2, Physics Q29

Question 29 of 90 in this shift, Physics question 29 of 30, Section B.

A coil in the shape of an equilateral triangle of side 10 cm lies in a vertical plane between the pole pieces of permanent magnet producing a horizontal magnetic field 20 mT. The torque acting on the coil when a current of 0.2 A is passed through it and its plane becomes parallel to the magnetic field will be

\sqrt{x}\times10^{-5}

Nm. The value of

x

is __________.

Official answer

NTA final key.

Chapter: Moving Charges and Magnetism
Topic: Magnetic Dipole Moment
Idea tested: Torque on a dipole in uniform field

Same idea in other shifts

Asked 6× in all

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
8 Apr 2026, Shift 2 · Q39A current carrying circular loop of radius 2 cm with unit normal $\hat{n} = \frac{\hat{k} + \hat{i}}{\sqrt{2}}$ is placed in a magnetic…MediumSingle correct
31 Jan 2024, Shift 2 · Q42A uniform magnetic field of $2\times10^{-3}$ T acts along positive $Y$ -direction. A rectangular loop of sides 20 cm and 10 cm with current…MediumSingle correct
3 Sep 2020, Shift 2 · Q24A galvanometer coil has 500 turns and each turn has an average area of $3 \times 10^{-4}$ m $^2$ . If a torque of 1.5 Nm is required to keep…EasyNumerical value
5 Sep 2020, Shift 1 · Q15A square loop of side 2a, and carrying current I, is kept in XZ plane with its centre at origin. A long wire carrying the same current I…HardSingle correct

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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.