Question

A current of 1 ampere is passed through a straight wire of length 2.0 m. What will be the magnetic field at a point in air at a distance of 0.3 m from either end of the wire and lying on the axis of wire?

• A. $\frac{{\mu }_0}{2\pi }$
• B. $\frac{{\mu }_0}{4\pi }$
• C. $\frac{{\mu }_0}{8\pi }$
• D. Zero

Answer 1

The correct option is D Zero

The magnetic field on any point on the axis of wire is zero, as the magnetic field lie perpendicular to the wire carrying current. Hence, $\overrightarrow{B}$ at a point in air at a distance 0.3 m from either end of the wire and lying on the axis of wire will be zero.