A closely wound coil of 50 turns and radius 15 cm carries a current 3 A. The magnetic moment of the coil is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → \( 10.59\,\mathrm{A\,m^{2}} \)
A current loop is a magnetic dipole whose moment is the current times the area, and a coil of \( N \) turns has that moment multiplied by the number of turns.
\( \displaystyle m = N\,I\,A = N\,I\,\pi r^{2} \)
\( N = 50 \)
\( I = 3\,\mathrm{A} \)
\( r = 15\,\mathrm{cm} = 0.15\,\mathrm{m} \)
\( \displaystyle m = 50 \times 3 \times \pi \times (0.15)^{2} = 3.375\,\pi \approx 10.6\,\mathrm{A\,m^{2}} \)
The nearest option is \( 10.59\,\mathrm{A\,m^{2}} \).
Note: NTA picked this question from an NCERT (2026-27) example and changed the figures. Do not ignore NCERT while practising numericals.
NCERT (2026-27):
Torque on Current Loop, Magnetic Dipole – …
