The current of 10.0 nA is established in a circular loop of radius 5.0 cm. The magnetic dipole moment of the current loop is-
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 7.85 × 10−11 Am2
A current loop behaves as a magnetic dipole whose magnetic moment is the current multiplied by the area of the loop.
\( \displaystyle m = IA = I\pi r^{2} \)
\( I = 10.0\,\mathrm{nA} = 1.0\times10^{-8}\,\mathrm{A} \)
\( r = 5.0\,\mathrm{cm} = 5.0\times10^{-2}\,\mathrm{m} \)
\( \displaystyle m = 1.0\times10^{-8}\,\mathrm{A} \times 3.14 \times (5.0\times10^{-2}\,\mathrm{m})^{2} \)
\( \displaystyle m = 1.0\times10^{-8} \times 7.85\times10^{-3}\,\mathrm{A\,m^{2}} \)
\( \displaystyle m = 7.85\times10^{-11}\,\mathrm{A\,m^{2}} \)