Q. A long straight wire carries a current of $\pi\ amp$. The magnetic field due to it will be $5 \times 10^{- 5}weber/m^{2}$ at what distance from the wire [$\mu_{0} =$ permeability of air]
A) $10^{4}\mu_{0}\ metre$
B) $\frac{10^{4}}{\mu_{0}}\ metre$
C) $10^{6}\mu_{0}\ metre$
D) $\frac{10^{6}}{\mu_{0}}\ metre$
Explanation
(a) $B = \frac{\mu_{0}}{2\pi}\frac{i}{r} \Rightarrow 5 \times 10^{- 5} = \frac{\mu_{0}}{2\pi} \times \frac{\pi}{r} \Rightarrow r = 10^{4}\mu_{0}\ metre$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.