JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
Two concentric circular loops of radii \(r _{1}=30\,cm\) and \(r_{2}=50\,cm\) are placed in \(X - Y\) plane as shown in the figure. \(A\) current \(I=7\,A\) is flowing through them in the direction as shown in figure. The net magnetic moment of this system of two circular loops is approximately.
- A \(\frac{7}{2} \hat{ k } Am ^{2}\)
- B \(-\frac{7}{2} \hat{ k } Am ^{2}\)
- C \(7 \hat{ k } Am ^{2}\)
- D \(-7 \hat{ k } Am ^{2}\)
Answer & Solution
Correct Answer
(B) \(-\frac{7}{2} \hat{ k } Am ^{2}\)
Step-by-step Solution
Detailed explanation
\(\overrightarrow{ M }=- i \pi(0.5)^{2} \hat{ k }+ i \pi(0.3)^{2} \hat{ k }\) \(\overrightarrow{ M }=-7 \times \frac{22}{7}\left(\frac{25}{100}-\frac{9}{100}\right) \hat{ k }\) \(=-22\left(\frac{16}{100}\right) \hat{ k }\) \(\overrightarrow{ M }=-3.52 \hat{ k }\,Am ^{2}\)…
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