- Exam
- JEE Main
- Year
- 2022
- Date
- 26 July
- Shift
- Evening Shift
- Subject
- Physics
- Chapter
- Magnetic Effects of Current
JEE Main 2022 · 26 July · Evening Shift · Physics · Magnetic Effects of Current
Two concentric circular loops of radii r _ 1 = 30cm and r _ 2 =...
Two concentric circular loops of radii and are placed in plane as shown in the figure. A current is flowing through them in the direction as shown in figure. The net magnetic moment of this system of two circular loops is approximately
Options
- A\dfrac{7}{2}\overset{^}{k}A{m}^{2}
- B- \dfrac{7}{2}\overset{^}{k}A{m}^{2}
- C7\overset{^}{k}A{m}^{2}
- D- 7\overset{^}{k}A{m}^{2}
Correct answer
B. - \dfrac{7}{2}\overset{^}{k}A{m}^{2}
Step-by-step solution
Net magnetic moment of the system is
\overset{\to}{M} = - I{A}_{1}\overset{^}{k} + I{A}_{2}\overset{^}{k} (Here currents in both circular loops are in opposite direction)
\overset{\to}{M} = - I\pi{\left(0 . 5\right)}^{2}\overset{^}{k} + I\pi{\left(0 . 3\right)}^{2}\overset{^}{k}
\overset{\to}{M} = - 7 \times \dfrac{22}{7}\left(\dfrac{25}{100} - \dfrac{9}{100}\right)\overset{^}{k}= - 22\left(\dfrac{16}{100}\right)\overset{^}{k}
\overset{\to}{M} = - 3 . 52\overset{^}{k}A{m}^{2}
= - \dfrac{7}{2}\overset{^}{k}A{m}^{2}