A certain electric motor wire that carries a current of 4 A is perpendicular to a magnetic field of 0.8 T. The force acting on each cm of the wire is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 3.2 × 10−2 N
A straight conductor carrying a current in a magnetic field experiences the magnetic force on a current-carrying conductor, \( F = BIL\sin\theta \). The wire is perpendicular to the field, so \( \theta = 90^\circ \) and \( \sin\theta = 1 \).
\( B = 0.8\,\mathrm{T} \)
\( I = 4\,\mathrm{A} \)
\( L = 1\,\mathrm{cm} = 1\times10^{-2}\,\mathrm{m} \)
\( \displaystyle F = BIL\sin\theta \)
\( \displaystyle F = 0.8\,\mathrm{T} \times 4\,\mathrm{A} \times 1\times10^{-2}\,\mathrm{m} \times \sin 90^\circ \)
\( \displaystyle F = 3.2\times10^{-2}\,\mathrm{N} \)
This is the force on each centimetre of the wire.