JEE Mains · Physics · STD 12 - Moving charges and magnetism
- JEE Mains 2019
- Medium
- MCQ
A square loop is carrying a steady current \(I\) and the magnitude of its magnetic dipole moment is \(m\). If this square loop is changed to a circular loop and it carries the same current, the magnitude of the magnetic dipole moment of circular loop will be
Pick an option to check your answer.
Answer & Solution
Correct Answer
(C) \(\frac {4m}{\pi }\)
Step-by-step Solution
Detailed explanation
\(m = I{l^2}\) \(2\pi r = 4l\)
\({{{\text{m}}^\prime } = \frac{{I4{\ell ^2}}}{\pi }}\) \({{\text{r}} = \frac{{2\ell }}{\pi }}\)
\({{{\text{m}}^\prime } = \frac{{I4{\ell ^2}}}{\pi }}\) \({\pi {r^2} = \frac{{\pi 4{\ell ^2}}}{{{\pi ^2}}} = \frac{{4{\ell ^2}}}{\pi }}\)
\({{{\text{m}}^\prime } = \frac{4}{\pi }\,{\text{m}}}\)
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