Verified Solution • 2025–26 Session moderate

QJEEM22Phda9d: JEE Main 2022 Physics - Class 12 JEEM22Phda9d Solution: Two concentric circular loops of radii and are placed in plane…

Two concentric circular loops of radii r1=30 cmr_{1}=30 \mathrm{~cm} and r2=50 cmr_{2}=50 \mathrm{~cm} are placed in X−Y\mathrm{X}-\mathrm{Y} plane as shown in the figure. A current I=7 AI=7 \mathrm{~A} is flowing through them in the direction as shown in figure. The net magnetic moment of this system of two circular loops is approximately :

JEE Main 2022 (Online) 26th July Evening Shift Physics - Magnetic Effect of Current Question 82 English

Multiple Choice Options

  • A 72k^ Am2\frac{7}{2} \hat{k} \,\mathrm{Am}^{2}
  • B −72k^ Am2-\frac{7}{2} \hat{k} \,\mathrm{Am}^{2}
  • C 7 k^ Am2{7}\, \hat{k} \,\mathrm{Am}^{2}
  • D −7 k^ Am2{-7}\, \hat{k} \,\mathrm{Am}^{2}

Step-by-Step Verified Solution

μ1=πr12×I1{\mu _1} = \pi r_1^2 \times {I_1}

μ2=πr22×I2{\mu _2} = \pi r_2^2 \times {I_2}

∴\therefore μnet=(μ2−μ1)(−k^){\mu _{net}} = ({\mu _2} - {\mu _1})\left( { - \widehat k} \right)

=π(r22−r12)I(−k^)= \pi \left( {r_2^2 - r_1^2} \right)I\left( { - \widehat k} \right)

=3.142×(0.52−0.32)×7(−k^)= 3.142 \times \left( {{{0.5}^2} - {{0.3}^2}} \right) \times 7\left( { - \widehat k} \right)

=−72k^= - {7 \over 2}\widehat k Am2

Related Learning Resources & Exam Preparation

JEE Main PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring