A long straight conductor carries a current of 304 A. The magnitude of the magnetic field due to the current at a distance of 6 cm from the conductor is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 1.013 mT
By Ampere's law the field at a distance \( r \) from a long straight wire is \( B = \mu_0 I/2\pi r \).
\( \displaystyle r = 6\,\mathrm{cm} = 0.06\,\mathrm{m} \)
\( \displaystyle B = \frac{2\times10^{-7}\times304}{0.06} = 1.013\times10^{-3}\,\mathrm{T} = 1.013\,\mathrm{mT} \)
Note: NTA picked this question from an NCERT (2026-27) exercise and changed the figures. Do not ignore NCERT while practising numericals.
NCERT (2026-27):
Exercises – …
